Rebecca Works as a Penetration Tester in a Security Service

Rebecca works as a Penetration Tester in a security service firm named Xsecurity. Rebecca placed a sniffer on a subnet residing deep inside the client's network. She used the Firewalk tool to test the security of the company's network firewall. After the test, when Rebecca checked the sniffer logs, she was unable to see any traffic produced by the Firewalk tool. What is the reason for this?

A) Rebecca does not see any of the Firewalk traffic because it sets all packets with a TTL of one.
B) Network sniffers cannot detect Firewalk so that is why none of the traffic appears.
C) Firewalk cannot pass through firewalls.
D) She cannot see the traffic because Firewalk sets all packets with a TTL of zero.