Which cells of the retina enable us to see coloured objects around us?

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.

In which part of the sclera blood capillaries are absent?

The eye is developed from which germ layer?

Photosensitive compounds are formed of which substances?

During the night,when light intensity is low,it is detected by: