What is the purpose of the VLAN1 interface?

What is the purpose of the VLAN1 interface?

A.
It provides the ScreenOS device with a routable IP address while operating in route mode.

B.
It provides policy-based NAT for 802.1Q VLANs.

C.
It provides an interface that can be used with 802.1Q VLANs in transparent mode.

D.
It provides an interface that can be used to remotely manage the ScreenOS device while operating in transparent mode.