Question: Which protocol(s) are mandated for transporting subscription/notification related signaling over the CSC-3 reference point between an MC Service Server and a Group Management Server?
Option 1: SIP-2 and SIP-3
Option 2: HTTP-1 and HTTP-2
Option 3: Both SIP (SIP-2, SIP-3) for subscription/notification and HTTP (HTTP-1, HTTP-2) for non-subscription/notification
Option 4: Only SIP-3 when servers are on the same SIP core
Explanation: According to specifications, SIP-2 and SIP-3 handle subscription/notification related signaling over the CSC-3 reference point. SIP-3 is used across different SIP cores, implying SIP-2's use within the same core, thus both are correct for this context.