Question: In an Evolved Universal Terrestrial Radio Access Network (E-UTRAN), what triggers a User Equipment (UE) to set the `failureType` as `randomAccessProblem` in the MCGFailureInformation message?
Option 1: Expiry of T310 timer, indicating a connection setup failure.
Option 2: Reaching the maximum number of retransmissions at the Medium Access Control (MAC) layer for Multicast Groups.
Option 3: Receipt of a specific error code from the Serving Gateway (S-GW) during handover.
Option 4: Initiation of MCGFailureInformation message transmission due to random access problem indication from MCG MAC.
Explanation: This is correct because, according to the specified protocol behavior, if the UE initiates transmission of the MCGFailureInformation message to provide a random access problem indication from the Multicast Group (MCG) Medium Access Control (MAC), it sets the `failureType` as `randomAccessProblem`. This directly relates to issues encountered during the random access process in the MAC layer for multicast communications.