Why must you use aggressive mode when a local FortiGate IPsec gateway hosts multiple dialup tunnels?

Why must you use aggressive mode when a local FortiGate IPsec gateway hosts multiple dialup tunnels?

Response:
A . The FortiGate is able to handle NATed connections only with aggressive mode.
B . FortiClient supports aggressive mode.
C . The remote peers are able to provide their peer IDs in the first message with aggressive mode.
D . Main mode does not support XAuth for user authentication.

View Answer

Answer: C