BSI (British Standards Institution) Group Korea (hereinafter referred to as the "Assurer") was requested to verify the SK D&D ESG Report (hereinafter referred to as the "Report"). The Assurer is independent of SK D&D and has no major operational financial interest other than the assurance. This assurance opinion statement is intended to provide information related to the assurance of the SK D&D report relating to the environment, social and governance (ESG) to the relevant stakeholders and may not be used for any purpose other than the purpose of publication. This assurance opinion statement was prepared based on the information presented by the SK D&D and the assurance was carried out under the assumption that presented the information and data were complete and accurate.

SK D&D is responsible for managing the relevant information contained within the scope of assurance, operating the relevant internal control procedures, and for all information and claims contained in the report. Any queries that may arise by virtue of this independent assurance opinion statement or matters relating to it should be addressed to SK D&D only.

The Assurer is responsible for providing SK D&D management with an independent assurance opinion containing professional opinions derived by applying the assurance methodology to the scope specified, and to provide the information to all stakeholders of SK D&D. The Assurer shall not bear any other responsibility, including legal responsibility, to any third party other than SK D&D in providing the assurance opinion and shall not be liable to any other purpose, purpose or stakeholders related thereto for which the assurance opinion may be used.

The scope of engagement agreed upon with SK D&D includes the following:

• Reporting contents during the period from January 1st to December 31st 2024 included in the report, some data included the first half of 2025.
• Major assertion included in the Report, such as sustainability management policies and strategies, goals, projects, and performance, and the Report contents related to material issues determined as a result of materiality assessment.
• Appropriateness and consistency of processes and systems for data collection, analysis and review.
• In Accordance with the four principles of AA1000 AccountAbility in the report, based on the type of Sustainability Assurance based on AA1000AS v3 and if applicable, the reliability of the sustainability performance information contained in the report.

The following contents were not included in the scope of assurance.

• Financial information in Appendix.
• Index items related to other international standards and initiatives other than the GRI.
• Other related additional information such as the website, business annual report.

The assurance levels and types are as follows;

• Moderate level based on AA1000 AS and Type 2 (confirmation to the four principles as described in the AA1000 Accountability Principle 2018 and quality and reliability of specific performance information published in the report.)

Based on the scope and methodology of assurance applied, the assurer reviewed the following Disclosures based on the sampling of information and data provided by SK D&D.

[Universal Standards]

2-1 to 2-5 (The organization and its reporting practices), 2-6 to 2-8 (Activities and workers), 2-9 to 2-21 (Governance), 2-22 to 2-28 (Strategy, policies and practices), 2-29 to 2-30 (Stakeholder engagement), 3-1 to 3-3 (Material Topics Disclosures)

[Topic Standards]

201-1~2, 203-1, 205-1~3, 206-1, 302-1~5, 303-3, 303-5, 304-1, 304-4, 305-1~5, 306-1~3, 401-1~3, 403-1~9, 404-1~2, 405-1~2, 413-1, 414-1~2, 418-1

As a part of its independent assurance, the Assurer has used the methodology developed for relevant evidence collection in order to comply with the verification criteria and to reduce errors in reporting. The Assurer has performed the following activities;

• A top-level review of issues raised by external parties that could be relevant to organizations policies to provide a check on the appropriateness of statements made in the report.
• Discussion with managers and staffs on organization’s approach to stakeholder engagement.
• Review of the supporting evidence related to the material issues through interviews with senior managers in the responsible departments.
• Review of the system for sustainability management strategy process and implementation
• Review of materiality issue analysis process and prioritization by reviewing materiality issue analysis process and verifying the results
• Verification of data generation, collection and reporting for each performance index and document review of relevant systems, policies, and procedures where available
• An assessment of the company's reporting and management processes concerning this reporting against the principles of Inclusivity, Materiality, Responsiveness and Impact as described in the AA1000 AccountAbility Principles Standard (2018).
• Visit of the SK D&D Pan-Gyo Office to confirm the data collection processes, record management practices.

The Assurer performed limited verification for a limited period based on the data provided by the reporting organization. It implies that no significant errors were found during the verification process, and that there are limitations related to the inevitable risks that may exist. The Assurer does not provide assurance for possible future impacts that cannot be predicted or verified during the verification process and any additional aspects related thereto.

Among the GRI Topic Standards, the following disclourse were carried out in the assurance Type 2 based on the information and data provided by the reporting organization. In order to verify the reliability and accuracy of the data and information, internal control procedures related to data processing, processing, and management were verified through interviews with the responsible department, and accuracy was verified through sampling. Errors and intentional distortions in sustainability performance information included in the report were not found through assurance processes. The reporting organization manages the sustainability performance information through reliable internal control procedures and can track the process of deriving the source of the performance. Errors and unclear expressions found during the assurance process were corrected during the assurance process and prior to the publication of the report, and the assurer confirmed the final published report with the errors and expressions corrected.

• GRI Topic Standards: 201-2, 205-1~3, 206-1, 302-1~5, 303-3, 303-5, 305-1~5, 306-3, 401-1~3, 403-1~9, 404-1~2, 405-1~2, 414-1~2

The assurer will provide the following comments to the extent that they do not affect the result of assurance;

Considering the key business characteristics,

• It may be helpful to advance the sustainability management system by identifying key stakeholders within the value chain and shaping sustainability strategies and objectives based on their needs.
• It may be helpful to ead the sustainability management system advancing the system for calculating sustainability performance indicators for ownership and operating assets and strengthening internal control procedures for those performance indicators.

SK D&D provided us with their self declaration of compliance within GRI Standards. Based on our review, we confirm that social responsibility and sustainable development indicators with reference to the GRI Index. The Assurer confirmed that the Report was prepared in accordance with the GRI Standards and the disclosures related to the Universal Standards and Topic Standards Indicators based on the data provided by SK D&D. The sector standard was not applied.