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 with statefull firewalls
D . Statefull firewalls do not work with packet filtering firewalls

Answer: B