Question: What is the primary purpose of the `Notify_Establish_Session` service operation in the context of V2X Application Enabler (VAE) Services?
Option 1: To initiate a session-oriented service request from the UE (User Equipment) to the VAE server.
Option 2: To notify the establishment of a session-oriented service by the VAE server.
Option 3: To terminate an existing session between the VAE server and the UE.
Option 4: To modify the parameters of an already established session.
Explanation: The `Notify_Establish_Session` service operation is used by the VAE server to notify about the establishment of a session-oriented service, signaling the successful setup of a session from the server's end, crucial for managing and coordinating services in V2X communication scenarios.