question: What is the purpose of S-NSSAI based congestion control? [3GPP Release 18] option 1: To restrict data transfer via Control Plane CIoT 5GS Optimization option 2: To avoid and handle NAS signalling congestion for UEs with a back-off timer associated with or without an S-NSSAI option 3: To handle overload situations in the SMF option 4: To apply congestion control to a specific group of UEs 