Refer to the exhibit.

What is causing the error to occur on the MST switch?

A.
When a PVST+ switch is connected to an MST switch, the IST root (MST0) needs to be the
root for all PVST+ spanning trees.

B.
When a PVST+ switch is connected to an MST switch, interaction between MST and PVST+ is
not supported

C.
When a PVST+ switch is connected to an MST switch, root guard should be disabled on a perport basis.

D.
When a PVST+ switch is connected to an MST switch, the PVST+ switch must be the root for
all MST instances.