Four words have been given, out of which three are alike in some manner and one is different. Select the odd one.

Pupil, Cochlea, Cornea, Iris

Pupil, Cochlea, Cornea, Iris 

Pupil: A part of the eye that regulates the amount of light entering.

Cochlea: A part of the inner ear responsible for hearing.

Cornea: A part of the eye that covers the front and helps focus light.

Iris: A part of the eye that controls the size of the pupil. 

The odd one out is Cochlea, as it is related to the ear, while the other three (Pupil, Cornea, and Iris) are related to the eye.

So, Cochlea  is an odd one 

Thus, correct answer is (a ) Cochlea ​​