Question: In V2X communication, as per 3GPP security specifications, what protocol is utilized for authorizing access to VAE (Vehicle-to-Everything Application Enabler) service APIs, based on local configuration using the "Client Credentials" grant?
Option 1: OAuth2 protocol
Option 2: TLS (Transport Layer Security) protocol
Option 3: DTLS (Datagram Transport Layer Security) protocol
Option 4: IPSec (Internet Protocol Security)
Explanation: OAuth2 is specifically mentioned as the protocol for authorizing access to VAE service APIs, leveraging the "Client Credentials" authorization grant for local configuration purposes. TLS, while crucial for secure communication between servers (e.g., VAE server and V2X application specific server), is not directly involved in API access authorization. DTLS and IPSec are security protocols but are not referenced in this context for API access authorization.