What is the CORRECT definition of service management?

This describes service transition activities (moving services into live operation), which is one stage of the service lifecycle, not the definition of service management itself.

The official ITIL definition of service management is 'a set of specialized organizational capabilities for enabling value for customers in the form of services.' This definition emphasizes that service management is about organizational capability, not just people or processes. It frames the discipline around value creation and delivery rather than operational tasks alone.

This loosely describes demand management or service request fulfillment, neither of which is the definition of service management as a discipline.

This is an informal description of a service desk or operations team, not the formal ITIL definition of service management.