Which type of firewall can act on the behalf of the end device?

A.
Stateful packet

B.
Application

C.
Packet

D.
Proxy

Explanation:
BD
Application firewalls, as indicated by the name, work at Layer 7, or the application layer of the OSI model.
These devices act on behalf of a client (aka proxy) for requested services.
Because application/proxy firewalls act on behalf of a client, they provide an additional “buffer” from port scans,
application attacks, and so on. For example, if an attacker found a vulnerability in an application, the attacker
would have to compromise the application/proxy firewall before attacking devices behind the firewall. The
application/proxy firewall can also be patched quickly in the event that a vulnerability is discovered. The same
may not hold true for patching all the internal devices.
Source: http://www.networkworld.com/article/2255950/lan-wan/chapter-1–types-of-firewalls.html