In Vitro Testing Conditions That Can Be Modified to Enhance $\degree$

In vitro testing conditions that can be modified to enhance the expression of oxacillin resistance include all the following, except

A) use Mueller-Hinton media.
B) making final test readings after a full 24 hours of incubation.
C) incubation of tests at temperatures no greater than 35 $\degree$ C.
D) preparation of inocula using the direct inoculum suspension procedure.