Question: What action does the SMF take when it receives a PDU SESSION RELEASE REQUEST message for a PDU session that is in the INACTIVE state?
Option 1: The SMF sends a PDU SESSION RELEASE COMPLETE message to the UE.
Option 2: The SMF ignores the request and takes no further action.
Option 3: The SMF sends a PDU SESSION RELEASE REJECT message with cause #43 "Invalid PDU session identity" to the UE.
Option 4: The SMF transitions the PDU session to the ACTIVE state.
Explanation: When the SMF receives a PDU SESSION RELEASE REQUEST for an inactive PDU session, it responds with a rejection message containing cause #43 "Invalid PDU session identity", indicating that the requested action cannot be performed due to the current state of the PDU session.