Which statement about the Firewalk attack is true?

Which statement about the Firewalk attack is true?

A.
The firewall attack is used to discover hosts behind firewall device.

B.
The firewall attack uses ICMP sweep to find expected hosts behind the firewall.

C.
The firewall attack uses traceroute with a predetermined TTL value to discover hosts
behind the firewall.

D.
The firewall attack is used to find the vulnerability in the Cisco IOS firewall code.

E.
The firewall attack uses an ICMP echo message to discover firewall misconfiguration.