What happens if a source of bright light suddenly becomes bright in front of the eye?

Identify the part of the eye concerned with the following two sentences in the given figure. Which alphabet is used to indicate this part?
$1$. It is the coloured visible part of the eye.
$2$. It is a pigmented and opaque structure.

The lens and retina of the vertebrate eye are derived from:

$X -$ Rod cells' function is twilight (scotopic) vision.
$Y -$ Cone cells' function is daylight (photopic) vision.

Select the correct option based on the given sentences regarding the mechanism of vision:
$(I)$ Light rays in the visible wavelength are focused on the retina through the cornea and lens.
$(II)$ It generates impulses in rods and cones.
$(III)$ Photosensitive pigment is composed of an opsin (protein) and retinal (an aldehyde of vitamin $A$).
$(IV)$ Light induces the dissociation of retinal and opsin.
$(V)$ This process causes a change in membrane permeability,as a result,potential differences are generated in the photoreceptor cells.

The sensory pigmented layer of the eye is known as: