Which of the following are the key regulations applicable to the CSP facility?

The correct answer addresses the key regulations that pertain specifically to the operations and responsibilities of cloud service providers (CSPs) within the context of data security and privacy. COBRA, while important in its own right, primarily relates to healthcare coverage continuation after employment, not directly to the operational security of cloud services.

The other options, HITRUST CSF, PCI DSS, and HIPAA, are indeed relevant to CSPs, particularly when they handle sensitive information. HIPAA sets standards for the protection of health information, which is critical for CSPs that manage healthcare-related data. PCI DSS outlines security requirements for organizations that process credit card transactions. HITRUST CSF provides a framework for managing data protection, particularly in healthcare.

In contrast, as the question asks for key regulations specifically for a CSP facility rather than general knowledge of compliance frameworks or regulations that impact multiple sectors, the focus on COBRA does not align as closely with the direct regulatory environment impacting cloud services. Thus, even though the regulation in the question pertains to important aspects of compliance, its relevance to cloud services specifically does not hold as strong as the other options. It would be more appropriate to consider either PCI DSS or HIPAA in such discussions regarding CSP responsibilities regarding security compliance.