Which vitamin is essential for clear vision in dim light and whose deficiency causes night blindness?

Correct option is B

Vitamin A is essential for formation of visual pigments.
It plays a key role in rod cell function of the retina. Deficiency leads to night blindness (nyctalopia).
Prolonged deficiency causes xerophthalmia. Vitamin C and D have no role in vision.
Hence, Vitamin A is essential for dim light vision. Therefore, option (b) is correct.