The coarse and fine focus knobs adjust the distance between

a. the objective and ocular lenses.
b. the ocular lenses.
c. the ocular lenses and your eyes.
d. the stage and the condenser lens.
e. the stage and the objective lens.

The correct answer is: e. the stage and the objective lens.

Coarse Focus is the rough focus knob on the microscope used for the movement the of objective lenses toward or away from the specimen (located on the slice that is placed on the stage). On the other hand, fine focus is used to focus on various parts of the specimen.. Generally, coarse focus is used first to get close then moves to the fine focus knob for fine tuning.

there are so many examples for that in different areas, like biology experiment carried out in our lab recently.

here's one link: