Question: What happens to the "forbidden PLMNs for attach in S101 mode" list when the UE is switched off or when the USIM is removed?
Option 1: The list is updated with new PLMN identities.
Option 2: The list remains unchanged.
Option 3: The oldest PLMN identity is deleted.
Option 4: The list is erased.
Explanation: According to the specification, when the UE is switched off or when the USIM is removed, the "forbidden PLMNs for attach in S101 mode" list is erased. This ensures that the list does not retain any outdated information and starts fresh when the UE is restarted or a new USIM is inserted.