The correct answer is C.
OBJ-3.4: When configuring your SSH connection, you must ensure that a key is established between your client and the server. If you never setup an SSH key, you will need to generate a new key to get SSH to connect properly. Since the other technician was able to connect on her machine, we can rule out a SSH server issue, so it must be an issue with your account or client. The only option that relates solely to your account or client is the possibility that a key was not generated.