Which legislation must a trusted cloud service adhere to when utilizing the data of EU citizens?

The General Data Protection Regulation (GDPR) is the correct legislation that a trusted cloud service must adhere to when utilizing the data of EU citizens. GDPR is a comprehensive data protection law that came into effect in May 2018, specifically designed to enhance individuals' control over their personal data within the European Union. It establishes strict guidelines for the collection, processing, and storage of personal data and grants EU citizens several rights, including the right to access their data, the right to have their data erased, and the right to data portability.

Organizations that process data of EU citizens, regardless of their location, must comply with GDPR's requirements. This includes implementing technical and organizational measures to protect personal data, conducting impact assessments when necessary, and appointing data protection officers if required.

The other options do not pertain to the protection of EU citizens' data in the context of cloud services. Each of them addresses different regulatory areas: EMTALA relates to emergency medical treatment, APPI is a privacy law in Japan, and SOX deals with corporate financial practices and corporate governance. As such, these regulations do not apply in the context of managing personal data under EU legislation, affirming that GDPR is the relevant framework in this situation.