Question

a. what is the first thing you should do after placing the slide on the microscope stage?
switch to the highest magnification;
use the coarse focus knob;
click the nosepiece to the lowest magnification setting;
remove the slide and add a cover slip.

Explanation:

To use a microscope, after placing the slide on the stage, the first step is to set the nosepiece to the lowest magnification (usually the scanning objective) to start with a wider field of view for easier focusing. Switching to the highest magnification first is incorrect as it's hard to find the specimen. Using the coarse focus knob before setting the lowest magnification isn't the first step. Removing the slide to add a cover slip is wrong if the slide already has a cover slip (and the question doesn't indicate it needs one). So the correct action is to click the nosepiece to the lowest magnification setting.

Answer:

C. Click the nosepiece to the lowest magnification setting.