Question: In the context of Diameter interworking with packet data networks, what does the absence of `Visited-PLMN-Id` AVPs within the `Restricted-PLMN-List` AVP imply for Enhanced Coverage?
Option 1: Enhanced Coverage is restricted in all serving PLMNs.
Option 2: Enhanced Coverage settings are currently not defined.
Option 3: The current visited PLMN does not support Enhanced Coverage.
Option 4: Enhanced Coverage is allowed in all serving PLMNs.
Explanation: The absence of `Visited-PLMN-Id` AVPs within the `Restricted-PLMN-List` AVP indicates that there are no specific serving PLMNs where Enhanced Coverage is restricted, thereby implying that Enhanced Coverage is allowed in all serving PLMNs.