Read the assertion and reson carefully to mark the correct option out of the options given below:
Assertion : Circular smooth muscles of iris contract when bright light falls on the eye .
Reason : Pupil gets constricted by the contraction of circular smooth muscles of iris .

Options

A. If both the assertion and the reason are true and the reason is a correct explanation of the assertion
B. If both the assertion and the reason are true but the reason is a not correct explanation of the assertion
C. If the assertion is true but the reason is false
D. If both the assertion and reason are false

Answer

B

Explanation

The wall of each eyeball is made up of three concentric layer-sclerotic, choroid and retina. The choriod is a highly vascular pigmented layer separating the the sclerotic from the inner layer of the eyeball. It is connected in front to a thick structrure called cillary body. Iris is a pigmented, muscular, opaque diaphragm which extends from the cillary body in front of a biconvex trasnparent lens, iris has a small central biconvex trasnparent lens. iris has a small central aperture called pupil. Light passing through the comes enters through the pupil to fall on the lens behind it. The iris has two sets of smooth muscles arranged circularly and radially around the pupil. the pupil get of circular msucles to reduce the amount of light falling on the lens. on the contrary. the pupil gets dilated by the contraction of radial muscles to increase the amount of light falling on the lens.