Question: What protocol can be used as an operator option for providing Authentication, Authorization, and Accounting services on the Gi/Sgi interface?
Option 1: RADIUS
Option 2: HTTP
Option 3: FTP
Option 4: Diameter
Explanation: The correct answer is Diameter because it is specifically mentioned in the context of providing Authentication, Authorization, and Accounting services on the Gi/Sgi interface. Diameter protocol can be used by a GGSN/P-GW to authenticate users and provide accounting information to a Diameter server on a per APN basis.