How does the VCS Expressway allow secure traversal of a firewall?

How does the VCS Expressway allow secure traversal of a firewall?

A.
It uses a designated port to allow all traffic to pass through the firewall

B.
It takes the place of a firewall to control trusted messages using a pre-set list of destinations

C.
It makes outbound connections only

D.
It prohibits all incoming and outgoing message from untrusted destinations