Which best describes the role of a proxy server?

A.
A device that inspects Layer 2 – Layer 4 traffic running through it and denies or permits based
on a set of policies.

B.
An intermediary program, which acts as both a server and a client for the purpose of making
requests on behalf of other clients.

C.
An intermediary program that protects the resources of a private network from users on other
networks.

D.
A device that extracts the destination address of a packet, selects ten best path for the packet
and forwards the packet the next device in the path.

Explanation:
http://www.w3.org/Protocols/rfc2616/rfc2616-sec1.html(search proxt)