You Cannot Find Material on a Gram Stained Cerebrospinal Fluid

You cannot find material on a Gram stained cerebrospinal fluid slide to focus on using the 10X objective. You should

A) turn the slide over. It is upside down.
B) reset the microscope for Köhler illumination and refocus.
C) raise the condenser to allow more light on the slide.
D) focus on the frosted end of the slide and then move to the specimen area.