John is the network administrator for Frederickson Machinery in Tampa, Florida. Frederickson Machinery has one large office, and a number of smaller offices spread out around the city. John’s primary responsibility is to oversee the network equipment hat includes switches, routers, gateways and firewalls. John is the only employee allowed to make any changes or troubleshoot the network equipment so he has to run to any of the offices himself whenever there are any network issues. John is becoming more and more busy, so he wants to be able to remotely manage the network equipment as much as possible. He does not want to use telnet because of its inherent security flaws, so he decides to use SSH. John downloads a program from the Internet for SSH connections and attempts to connect to one of his routers at another office. After a short time, the following screen pops up on his computer:
Why was John not able to connect?

A.
He needs to turn off stateful inspection on his firewalls

B.
He needs to open port 24 on his firewalls

C.
He needs to open port 22 on his firewalls

D.
Putty cannot make SSH connections