Question: What is the primary purpose of the CSC-1 reference point between the identity management client and the identity management server in the context of mission critical services?
Option 1: To facilitate direct communication between MC service clients and application servers
Option 2: To manage Quality of Service (QoS) parameters for mission critical communications
Option 3: To handle billing and subscription information for MC service users
Option 4: To enable authentication of the common services core to the MC service client and subsequent user authentication on behalf of applications
Explanation: The correct answer, Option 4, highlights the authenticating role of the CSC-1 reference point. This is crucial in mission critical services where secure access to services and verification of users/applications are paramount. The other options (1, 2, and 3) are incorrect because they describe functions unrelated to the primary purpose of CSC-1 as defined by its role in authentication processes within the mission critical services architecture.