Assuming this diagram represents an internal facility and the organization is implementing a firewall protection program, where should firewalls be installed?

Assuming this diagram represents an internal facility and the organization is implementing a firewall protection program, where should firewalls be installed?

A.
No firewalls are needed

B.
Op-3 location only

C.
MIS (Global) and NAT2

D.
SMTP Gateway and op-3

Explanation:
The objective of a firewall is to protect a trusted network from an untrusted network; therefore, locations needing firewall implementations would be at the existence of the external connections. All other answers are incomplete or represent internal connections.