Question: What is the primary purpose of entity authentication in the context of 3GPP security architecture?
Option 1: To establish a secret cipher key between the user and the serving network.
Option 2: To corroborate the user identity and ensure the user is connected to an authorized serving network.
Option 3: To provide integrity protection for user data transmission.
Option 4: To manage the maximum number of local authentications using the derived integrity key.
Explanation: Entity authentication in the context of 3GPP security architecture aims to achieve two primary objectives: user authentication and network authentication. User authentication ensures that the serving network corroborates the user's identity, while network authentication guarantees that the user is connected to a serving network authorized by the user's Home Environment (HE) to provide services. This is essential for maintaining the security and integrity of the network and user data.