Question: Under what conditions may the AMF skip the authentication procedure during the registration procedure for mobility and periodic registration update?
Option 1: When the UE has an established 5GS security context.
Option 2: When the UE is in 5GMM-IDLE mode.
Option 3: When the target cell is a dedicated network cell.
Option 4: When the UE has only an emergency PDU session and no 5GS security context is available.
Explanation: According to the 3GPP specification, the AMF may skip the authentication procedure during the registration procedure for mobility and periodic registration update if the UE has only an emergency PDU session and no 5GS security context is available. This allows for a more streamlined process in emergency situations where time is critical.