which are valid modes for a switch port used as a VLAN trunk?

As a network technician, do you know which are valid modes for a switch port used as a VLAN trunk? (Choose three.)

A.
transparent

B.
auto

C.
on

D.
desirable

E.
blocking

F.
forwarding

Explanation:
Both the auto and on modes can be automatically switched to the desirable mode based on the topology.
A trunk port can be configured as one of the following 5 different modes: on, off, desirable, auto, or nonegotiate.