Answer:
D. diaphragm
Step-by-step explanation:
The question above is related to the different parts of the microscope. Among the choices above, it is the diaphragm that regulates the amount of light passing through the specimen. This is located below the stage (the platform where the slide of specimen is placed). With the help of the diaphragm, the intensity of light is controlled, which allows the observer to see the specimen in the best contrast.
Additional Information:
The arm links the base of the microscope to its head.
The base simply supports the microscope.
The body tube links the objective lenses to the eyepiece.