Application Level Firewalls are commonly a host computer running proxy server software, which
makes a?

A.
Proxy Client

B.
Proxy Session

C.
Proxy System

D.
Proxy Server

Explanation:
A proxy server is a server that sits between a client and server application, such as
a Web browser and a source web server. It intercepts all requests to the real server to see if it can
fulfill the requests itself. If not, it forwards the request to the original source web server. Firewalls
usually provides this kind of services to have more control over user request and allow / deny the
traffic of those through the gateway. At this time the most common Proxy server is for HTTP
protocol, we can also have proxies for SMTP and FTP.