Question: In the context of IP Multimedia Subsystem (IMS), what is a required input for the Nhss_ImsSDM_Subscribe service operation to authorize updates for an NF consumer, alongside the NF Type and Key for each IMS Subscriber data type(s)?
Option 1: Application Server Identity
Option 2: IMS Subscriber's Location Information
Option 3: Supported Communication Services (e.g., Voice, Video)
Option 4: IMS Subscriber data type(s)
Explanation: The Nhss_ImsSDM_Subscribe service operation necessitates that the NF consumer specifies what type of IMS subscriber data it wishes to receive updates for. This is crucial for the HSS (Home Subscriber Server) to verify the NF consumer's authorization for those specific data types, ensuring controlled access to sensitive information. Thus, specifying the IMS Subscriber data type(s) is mandatory for the operation to proceed, making it a required input alongside the NF Type and respective keys.