Question: What action is the UE allowed to take when it receives a paging message during the UPDATE-NEEDED state?
Option 1: The UE can send user data.
Option 2: The UE can send signalling information as a response to the paging message.
Option 3: The UE can only perform cell selection/reselection.
Option 4: The UE cannot take any action until it enters a new substate.
Explanation: According to the specifications, during the UPDATE-NEEDED state, the UE is allowed to send signalling information as a response to paging or to initiate signalling for emergency services or emergency services fallback.