What type of firewall must you implement to abide by this policy?

You are assisting a Department of Defense contract company to become compliant with the stringent security policies set by the DoD. One such strict rule is that firewalls must only allow incoming connections that were first initiated by internal computers .

What type of firewall must you implement to abide by this policy?
A . Packet filtering firewall
B . Circuit-level proxy firewall
C . Application-level proxy firewall
D . Stateful firewall

Answer: D