Blindness in a child is most commonly due to -: (A) Keratomalacia, (B) Congenital cataract, (C) Glaucoma, (D) Injuries
Answer is A. Keratomalacia is due to vitamin A deficiency.

"Vitamin A deficiency is the most common cause of blindness in children in India". __ Philip Reily
"Vitamin A deficiency is the single most important cause of blindness in children". — Wykoff