The nictitating membrane, also known as the $Plica \text{ } semilunaris$, is a vestigial organ present in which part of the human eye?

Good vision depends on adequate intake of carotene-rich food. Select the most appropriate option from the following statements.
$I.$ Vitamin $A$ derivatives are formed from carotene.
$II.$ Photopigments are embedded in the membrane discs of the outer segment.
$III.$ Retinal is a derivative of Vitamin $A$.
$IV.$ Retinal is a part of all photopigments that absorb light.

Myopia (near-sightedness) in the human eye is a defect in which the image is formed...

The optic nerve is the:

Read the following statements with respect to the human eye and select the correct option.
Statement $I$: Uvea is the middle,vascular,and non-pigmented layer of the eye that lies outer to the retina.
Statement $II$: The size of the lens can be adjusted depending on the distance of the object from the eye,through the muscles of the ciliary body and the suspensory ligament.

The iris of an eye is an extension of which layer?