Question: When does the MME include the UE Additional Security Capability Information Element (IE) in a SECURITY MODE COMMAND?
Option 1: During every attach or tracking area updating procedure.
Option 2: Only when the ATTACH REQUEST or TRACKING AREA UPDATE REQUEST message included a UE additional security capability IE and the MME is initiating a SECURITY MODE COMMAND during an attach or tracking area updating procedure.
Option 3: When the MME does not support handling of UE additional security capabilities.
Option 4: During every detach or tracking area updating procedure.
Explanation: The correct answer is Option 2 because, according to the specification, the MME includes this IE only when specific conditions are met: the MME supports handling of UE additional security capabilities, it's initiating a SECURITY MODE COMMAND during an attach or tracking area updating procedure, and the ATTACH REQUEST or TRACKING AREA UPDATE REQUEST message included a UE additional security capability IE.