Question: What happens to a UE in CM-CONNECTED state when the AN signalling connection is released?
Option 1: The UE remains in CM-CONNECTED state.
Option 2: The UE enters CM-IDLE state, but only if it was previously in RRC_ACTIVE state.
Option 3: The UE enters CM-IDLE state and releases all ongoing NAS signalling procedures.
Option 4: The UE enters CM-IDLE state whenever the AN signalling connection is released (entering RRC_IDLE state over 3GPP access or when the release of the UE-N3IWF connectivity over untrusted non-3GPP access or the UE-TNGF connectivity over trusted non-3GPP access is detected by the UE).
Explanation: According to the text, a UE in CM-CONNECTED state shall enter CM-IDLE state whenever the AN signalling connection is released. This includes entering RRC_IDLE state over 3GPP access or when the release of the UE-N3IWF connectivity over untrusted non-3GPP access or the UE-TNGF connectivity over trusted non-3GPP access is detected by the UE.