The most abundant elements by mass in the body of a healthy human adult are : Oxygen (61.4%); Carbon (22.9%), Hydrogen (10.0%) ; and Nitrogen (2.6%). The weight which a 75 kg person would gain if all $^1H$ atoms are replaced by $^2H$ atoms is :

Question

( A ) 10 kg
( B ) 7.5 kg
( C ) 37.5 kg
( D ) 15 kg