Question: What is the state of a UE when it has initiated a tracking area update procedure and is waiting for a response from the MME?
Option 1: EMM-DEREGISTERED
Option 2: EMM-TRACKING-AREA-UPDATING-INITIATED
Option 3: EMM-REGISTERED
Option 4: EMM-SERVICE-REQUEST
Explanation: The UE enters the state EMM-TRACKING-AREA-UPDATING-INITIATED after initiating a tracking area update procedure and is waiting for a response from the MME, indicating that this state is associated with ongoing tracking area updating procedures.