Which of the following is the BEST way to accomplish this?

A user wants to know how to set up SSH (Secure Shell) to communicate between systems without requiring passwords. Which of the following is the BEST way to accomplish this?

A.
Use ssh-keygen to generate public-private keys.

B.
Use RSH (Remote Shell) rather than SSH because it does not require passwords.

C.
Disable passwords on specific accounts that will use SSH.

D.
Add systems that do not need passwords to the /etc/ssh.hosts file.