Question: What is the requirement for supporting Home Network triggered primary authentication in a 5G system?
Option 1: Both the Home Network (HN) and Serving Network (SN) must mandatorily support it.
Option 2: Support of Home Network triggered primary authentication is optional for both the HN and SN.
Option 3: Only the Home Network (HN) needs to support it, while the Serving Network (SN) does not have any specific requirement.
Option 4: The Serving Network (SN) must support it, but there is no such requirement for the Home Network (HN).
Explanation: According to the security architecture and procedures for a 5G system, both the HN and SN have the option to support or not support Home Network triggered primary authentication. This flexibility allows networks to choose their level of participation in this authentication process based on their specific needs and capabilities.