Question: What type of authentication is provided by the successful use of keys resulting from authentication and key agreement in subsequent procedures between UE and network?
Option 1: Explicit Key Authentication
Option 2: Mutual Authentication
Option 3: Implicit Key Authentication
Option 4: Certificate-based Authentication
Explanation: According to the security architecture of the 5G system, serving network authentication is provided through implicit key authentication. This means that authentication is implied by the successful use of keys resulting from authentication and key agreement in subsequent procedures, rather than an explicit authentication process.