The part of an eye which acts like a diaphragm of a photographic camera is

In the retina of the human eye,the cones are concentrated more at the

Identify the correct sequence of cells in the retina from the outside to the inside.

The middle layer of the human eye,the choroid,contains $A$ and looks $B$ in color. Choose the correct option for $A$ and $B$.

The point in the eye of mammals from which optic nerves and blood vessels leave the eyeball is known as:

$A$: Sharpest vision is in fovea centralis.
$R$: The relationship of receptor to bipolar cells to ganglion cells is $1:1:1$ within fovea centralis.