Answer:
C. diaphragm
Step-by-step explanation:
Microscope is very important instrument in biology and use to magnify the specimen or other biological objects.
Eyepiece, stage, diaphragm and revolving nosepiece are some of the important part of the microscope with different functions. such as Eyepiece carry the Ocular lens that helps to look the specimen, stage allows light to pass through, diaphragm regulates the amount of light reaches the eyepiece, and revolving nosepiece are use to change magnification.
So, Diaphragm controls the light that passes up toward the eyepiece and help in viewing the specimen. Diaphragm is located below the stage and above the condenser.
Hence, the correct answer is "C. diaphragm".