Question: What is the primary reason for a UE to enter the "EMM-REGISTERED.UPDATE-NEEDED" state, where it cannot initiate any EMM procedure except tracking area updating or combined tracking area updating?
Option 1: The UE's access class is blocked due to access class control.
Option 2: The network has rejected the NAS signalling connection establishment.
Option 3: The UE has lost coverage and is out of range of the current cell.
Option 4: The UE has initiated a service request as a response to paging.
Explanation: In this state, the UE is unable to initiate most EMM procedures due to being barred from accessing the current cell. This can occur when the access class is blocked due to access class control, which restricts certain types of UEs from accessing the network.