Explanation:

The Cloud Security Alliance (CSA) defines several operational domains in its Cloud Controls Matrix (CCM) and Security Guidance for Critical Areas of Focus in Cloud Computing. One of the key operational domains is:

• Portability and Interoperability – This deals with how easily data and applications can move between different cloud providers (portability) and how well they work together (interoperability), which is a major concern in cloud security and vendor lock-in.

Other options:

• (A) Scalability – This is a technical feature of cloud systems, not a defined CSA operational domain.
• (C) Flexibility – Also a general benefit of cloud computing, but not a CSA domain.
• (D) None of the mentioned – Incorrect, because (B) is a valid CSA domain.

✅ Final Answer: (B) Portability and interoperability