Question: What is the primary purpose of MAC-S (Message Authentication Code - S) in telecommunications, as utilized between the USIM (Universal Subscriber Identity Module) and the AuC (Authentication Centre)?
Option 1: To encrypt user data transmitted over the radio access network.
Option 2: To authenticate the identity of the UE (User Equipment) to the core network.
Option 3: To ensure confidentiality of signaling messages between the USIM and the AuC.
Option 4: To provide data origin authentication and integrity for synchronization failure information, specifically for RAND, SQN, and AMF.
Explanation: MAC-S is specifically designed to authenticate the source of synchronization failure information (ensuring it comes from the legitimate USIM) and verify the integrity of the included data elements (RAND, SQN, and AMF), preventing potential tampering or spoofing attacks. This aligns with the role of a Message Authentication Code in telecommunications security.