Question: When is the MBMS service de-registration of the GGSN performed?
Option 1: After authorisation of the first user on a particular GGSN, for a particular multicast MBMS Bearer service.
Option 2: When the last user leaves a particular GGSN, for a particular unicast MBMS bearer service.
Option 3: When the specific multicast MBMS service is initiated by BM-SC.
Option 4: When the last user leaves a particular GGSN, for a particular multicast MBMS bearer service.
Explanation: The correct answer is Option 4 because the MBMS service de-registration of the GGSN is performed when the last user leaves a particular GGSN, for a particular multicast MBMS bearer service. This ensures that resources are released and the service is terminated when no longer needed.