The eye is developed from which germ layer?

It contains derivatives of vitamin $- A$.

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

$A$: Retina is arranged anatomically in reverse order from what might be expected.
$R$: The receptor cells are towards the outside and ganglionic cells towards the inside,and light must pass through the nerve cells to reach them.

Colour blindness results from

The following figure is a diagram showing parts of the human eye. Identify $P, Q$,and $R$ from the options given below.
$\quad\quad P\quad\quad\quad Q\quad\quad\quad R$