Question: What is used to describe the EMM protocol of the UE and the network in the context of EPS?
Option 1: A single state machine
Option 2: Two different state machines for the UE and MME sides separately
Option 3: Two different state machines, one for the UE side and another for both the UE and MME sides combined
Option 4: Three or more state machines
Explanation: The EMM protocol of the UE and the network is described by means of two different state machines. One state machine describes the states of the EMM entity in the UE, while another state machine describes the states for the MME side.