What causes Beriberi?

Correct option is A

Beriberi is a disease caused by a deficiency of vitamin B1 (thiamine). Thiamine is essential for the proper functioning of the nervous system and the metabolism of carbohydrates. A deficiency of this vitamin can lead to neurological and cardiovascular symptoms characteristic of beriberi.Beri-Beri is of two type wet Beriberi and dry Beriberi.
Wet Beriberi affects the organs of circulatory system, while Dry Beriberi affects the nervous system and decreases muscle strength.