Which statement about the Cisco NAC CAS is true?

Which statement about the Cisco NAC CAS is true?

A.
The Cisco NAC CAS acts as a gateway between untrusted networks.

B.
The Cisco NAC CAS can only operate as an in-band real IP gateway.

C.
The Cisco NAC CAS can operate as an out-of-band virtual gateway.

D.
The Cisco NAC CAS is an administration and monitoring server.