How can you manually add an entry to your system’s ARP cache?

How can you manually add an entry to your system’s ARP cache?

A.
Directly edit /etc/arp-cache

B.
Run add-arp hostname FF:FF:FF:FF:FF:FF

C.
Run ping -a hostname

D.
Run arp -s hostname FF:FF:FF:FF:FF:FF

E.
Edit arp.conf and restart arpd