What is the reason that ProfiNET frames are discarded by default on Catalyst switches?

A.
ProfiNET uses a nonstandard Ethernet frame format

B.
The frames have an 802.1q tag with VLAN ID equal to 0 (zero)

C.
Catalyst switches do not support ProfiNET traffic

D.
A ProfiNET VLAN must be configured and enabled on a Catalyst switch