What property of ARP allows MAC addresses of frequently used servers to be fixed in the ARP table?

Question:
What property of ARP allows MAC addresses of frequently used servers to be fixed in the ARP table?

• A static IP-to-MAC address entry can be entered manually into an ARP table.
• Entries in an ARP table are time-stamped and are purged after the timeout expires.
• The type field 0x806 appears in the header of the Ethernet frame.
• The port-to-MAC address table on a switch has the same entries as the ARP table on the switch.

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