Question: What is the primary purpose of the PTP RAB ID element in the context of MBMS (Multimedia Broadcast Multicast Service) in a UTRAN (UMTS Terrestrial Radio Access Network)?
Option 1: To uniquely identify an MBMS Point-to-Point (PTP) radio bearer for a specific User Equipment (UE), facilitating association with an MBMS Radio Access Bearer (RAB) in the Radio Network Controller (RNC).
Option 2: To manage Quality of Service (QoS) parameters for dedicated channels in the uplink direction.
Option 3: To encode security credentials for authenticated access to MBMS services.
Option 4: To report UE capability information to the Serving GPRS Support Node (SGSN).
Explanation: The PTP RAB ID element's primary purpose is to identify an MBMS PTP radio bearer for a particular UE, enabling the RNC to associate it with an MBMS RAB, which is crucial for efficient management and delivery of MBMS services within the UTRAN infrastructure.