The correct way to open a port for SSH using firewalld is:
bash
firewalld-cmd --permanent --add-port=22/tcp
* This command allows TCP traffic on port 22 (the default port for SSH).
* Option B only displays saved rules and doesn't open the port.
* Option C contains incorrect syntax: --dport sshd is invalid (sshd is a daemon, not a port number).
* Option D removes the SSH service from the firewall, which is the opposite of the requirement.
Reference: CompTIA Linux+ XK0-005 Official Study Guide, Domain 3.0 - Security
"Use firewalld-cmd --permanent --add-port=22/tcp to allow SSH traffic through firewalld."