What are two reasons why this error would be displayed?

When attempting to remove a host from a vSphere Distributed Switch (vDS), an administrator observes the error message:
The resource ’16’ is in use
What are two reasons why this error would be displayed? (Choose two.)

A.
VMkernel network adapters on the vDS are in use.

B.
Virtual machine network adapters are connected to the vDS.

C.
Network I/O Control has been configured on the vDS.

D.
There is active network traffic on the vDS.

Explanation:
Explanation/Reference: