Why are vitamin `A` and vitamin `C` essential for us? Give their important sources.

Explanation

Vitamin `A` is essential for us because its deficiency causes xerophthalmia (hardening of the cornea of the eye) and night blindness.
Sources: Fish liver oil,. Carrots, bitter and milk. Vitamin `C` is essential for us because its deficiency causes scurvy (bleeding gums) and pyorrhea (loosening and bleeding of teeth).
Sources: Citrous fruits, amla, green leafy vegetables.