Question: What type of error occurs when an MBMS Session Start procedure cannot be performed due to missing required session attributes, such as QoS or MBMS Service Area?
Option 1: DIAMETER_ERROR_STOP_INDICATION
Option 2: DIAMETER_ERROR_START_INDICATION
Option 3: DIAMETER_ERROR_UNKNOWN_MBMS_BEARER_SERVICE
Option 4: DIAMETER_ERROR_SERVICE_AREA
Explanation: The error that occurs when an MBMS Session Start procedure cannot be performed due to missing required session attributes, such as QoS or MBMS Service Area, is specifically defined as DIAMETER_ERROR_START_INDICATION (5120). This error code indicates that the request failed and should not be attempted again.