Question

Which of the following would not be useful in trying to correct spherical aberration a. using a combination lens made up of lenses, each of which has a different index of refraction
b. using a circular stop to block out the outside rays of light
c. using proper grinding when an object is at a specific distance from the lens
d. using a diaphragm to block outside rays of light

Answer 1

A. Using a combination lens made up of lenses, each of which has a different index of refraction. Is the correct answer.

Answer 2

I am positive it is A took the test 
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