How does a Junos device learn about MAC addresses when II is first connected to an Ethernet LAN?

How does a Junos device learn about MAC addresses when II is first connected to an Ethernet LAN?
A . The device sends out a network broadcast message asking tor all devices and MAC
addresses on the network and stores this information In addition lo the interface from which the response was received.
B. The device learns the destination MAC addresses from traffic in the network and stores this MAC address in addition to the interface from which the traffic was received.
C. The device learns the source MAC addresses from traffic in the network and stores this MAC address in addition to the interface from which the traffic was received.
D. The device sends out a network multicast message asking for all devices and MAC addresses on the network and stores this Information in addition to the interface from which the response was received.

Answer: D