Why is that?

After passing her CEH exam, Carol wants to ensure that her network is completely secure. She implements a DMZ, statefull firewall, NAT, IPSEC, and a packet filtering firewall. Since all security measures were taken, none of the hosts on her network can reach the Internet. Why is that?

A.
IPSEC does not work with packet filtering firewalls

B.
NAT does not work with IPSEC

C.
NAT does not work withstatefull firewalls

D.
Statefull firewalls do not work with packet filtering firewalls