Answer: the attached file is the structure of the eye.
Click on it to view and know the highlighted structure.
The correct answer to the question is option A.
CONTROLLING THE SHAPE OF THE LENS.
Explanation: The ciliary muscle is one of the structure of the eye occupying a largest part of the ciliary body.
It is made up of smooth muscle fibers arranged in circular,radial and longitudinal direction.
The major function of the ciliary body is to change the shape of the lens and modify it's curvature inorder to maintain focus and accomodation.
The ciliary muscle also controls the flow of aqueous humor in the eyes.
When we view nearby objects,the ciliary muscles contracts causing the lens to become thicker attaining a more convex shape and decreasing it's curvature,this why during the dark,we have to strain and squeeze the eye inorder to see and focus clearly on an object.on the other hand,when we are looking at a far object,the ciliary muscle dilates causing the lens to become thinner, spreading out light and increasing it's curvature( concave shape).