What are two reasons that can trigger port1 to shut down?

Refer to the exhibits.

Port1 and port2 are the only ports configured with the same native VLAN 10.

What are two reasons that can trigger port1 to shut down? (Choose two.)
A . port1 was shut down by loop guard protection.
B . STP triggered a loop and applied loop guard protection on port1.
C . An endpoint sent a BPDU on port1 that it received from another interface.
D . Loop guard frame sourced from port 1 was received on port 1.

Answer: B, C