Which of the following structures of the eye can be artificially implanted?

Good vision depends on adequate intake of carotene-rich food. Select the best option from the following statements:
$(1)$ Vitamin $A$ derivatives are formed from carotene.
$(2)$ The photopigments are embedded in the membrane discs of the inner segment.
$(3)$ Retinal is a derivative of vitamin $A$.
$(4)$ Retinal is a light-absorbing part of all the visual photopigments.

The scotopic vision is developed through the stimulation of

Which of the following statements is correct?

In the yellow spot or fovea centralis,the cells present are

What is the cause of stereoscopic vision in humans?