A systems administrator configured firewall rules using firewalld. However, after the system is rebooted, the firewall rules are not present:

The systems administrator makes additional checks:

Which of the following is the reason the firewall rules are not active?

A. iptables is conflicting with firewalld.
B. The wrong system target is activated.
C. FIREWALL_ARGS has no value assigned.
D. The firewalld service is not enabled.