Relatively speaking, firewalls operated at the application level of the sevenlayer OSI model are:

A.
almost always less efficient.

B.
almost always less effective.

C.
almost always less secure.

D.
almost always less costly to setup.

E.
None of the choices.

Explanation:
Early attempts at producing firewalls operated at the application level of the seven-layer OSI model but this
required too much CPU processing power.
Packet filters operate at the network layer and function more efficiently because they only look at the header
part of a packet.