Question: In a USIM's MBMS security context, what happens if the integrity validation of the received MIKEY message fails?
Option 1: The USIM proceeds with the MGV-F procedure using a default MSK.
Option 2: The USIM returns a status word indicating 'Key freshness failure' (9865).
Option 3: The USIM abandons the function and returns a status word for 'Authentication error, incorrect MAC' (9862).
Option 4: The USIM requests a new MIKEY message with an updated Salt key.
Explanation: Integrity validation of the MIKEY message is crucial for ensuring authenticity and integrity. If this validation fails, indicating a potential security breach or corruption, the USIM must abort to maintain security. The correct response is returning an error for an authentication issue due to an incorrect Message Authentication Code (MAC), corresponding to status word '9862', preventing potentially compromised data from being processed further.