After plugging a host into a switch port, a user discovers that he can??t visit server resources on the network

After plugging a host into a switch port, a user discovers that he can??t visit server resources on the network. Why? (Select TWO).

A.
The computer is connected to an incorrectPoE port.

B.
The appropriate credentials have not been supplied for network access.

C.
The spanning tree protocol has locked down the port.

D.
The computer is connected to a port in the wrong VLAN.