Question: In the context of IP Multimedia (IM) Subsystem, what is the primary purpose of Implicit Registration as related to a user's Public User Identities?
Option 1: To limit a user to a single active Public User Identity at any given time.
Option 2: To enable a user to register multiple Public User Identities simultaneously without separate registration requests.
Option 3: To enhance security by requiring individual authentication for each Public User Identity.
Option 4: To simplify the deregistration process for users with multiple Public User Identities.
Explanation: Implicit Registration is designed to facilitate the concurrent registration of more than one Public User Identity for a user, streamlining the process by not requiring individual registration requests for each identity. This aligns with efficient management and utilization of resources within the IP Multimedia Subsystem, particularly in scenarios where users operate across multiple identities (e.g., personal and professional).