Curt has successfully compromised a web server sitting behind a firewall using a vulnerability in the web server program. He would now like to install a backdoor program but knows that all ports are not open inbound on the firewall. Which port in the list below will most likely be open and allowed to reach the server that Curt has just compromised? (Select the Best Answer)

A.
53

B.
25

C.
110

D.
69