Question: What is the purpose of the Home Network Private Key held by the ARPF?
Option 1: To derive CK' and IK' from K in case EAP-AKA' is used.
Option 2: To generate KAUSF from K in case 5G AKA is used.
Option 3: To deconceal the SUCI and reconstruct the SUPI by the SIDF.
Option 4: To store the latest KAUSF generated after successful completion of the latest primary authentication.
Explanation: The Home Network Private Key held by the ARPF is used by the SIDF to deconceal the SUCI and reconstruct the SUPI. This key material is crucial for secure communication between the UE and the network, ensuring that sensitive information remains protected.