What type(s) of firewalls provide(s) the greatest degree of protection and control because both firewall technologies inspect all seven OSI layers of network traffic?

A. A first-generation packet-filtering firewall
B. A circuit-level gateway
C. An application-layer gateway, or proxy firewall, and stateful-inspection firewalls
D. An application-layer gateway, or proxy firewall, but not stateful-inspection firewalls