Question: What additional identifier is used to identify standalone non-public networks in addition to PLMN ID?
Option 1: Network Slice Identifier
Option 2: Service Provider Identifier
Option 3: Access Point Name
Option 4: Network Identifier (NID)
Explanation: In the context of standalone non-public networks, an additional identifier is required to uniquely identify these networks. The correct answer is Network Identifier (NID), which is used in conjunction with PLMN ID for this purpose.