Question: In an Isolated Operation for Public Safety (IOPS) mode, what is the primary purpose of the MCPTT-IOPS-4 reference point between the IOPS distribution function and the MCPTT client?
Option 1: To establish dedicated voice channels for emergency services in uplink.
Option 2: For the management of user identities and authentication within the IOPS network.
Option 3: To facilitate the transmission of critical data over unicast in downlink.
Option 4: For IP multicast transmissions in downlink, utilizing the MB2-U reference point.
Explanation: The correct answer is Option 4 because the MCPTT-IOPS-4 reference point is specifically defined for handling IP multicast transmissions in the downlink direction. This is crucial for efficiently broadcasting mission-critical communications to multiple recipients simultaneously within an IOPS environment, leveraging the MB2-U reference point designed for group communication system enablers.