To disable root login over SSH, modify the /etc/ssh/sshd_config file using:

bash

sed -i 's/PermitRootLogin yes/PermitRootLogin no/' /etc/ssh/sshd_config

Then restart the SSH service:

bash

systemctl restart sshd

Options A, C, and D are invalid or syntactically incorrect.

Only B makes a valid and permanent configuration change.