What is done with LUNs that are NOT explicitly part of an I/O class?

NQM has been enabled. What is done with LUNs that are NOT explicitly part of an I/O class?

A.
Automatically placed in a background class

B.
I/Os are averaged across defined I/O classes

C.
LUNs are ignored by NQM

D.
Placed in the Unused LUNs class