The mass of a carbon atom is 1.994 × 10-23 grams. The mass of a hydrogen atom is 1.67 × 10-24 grams. What is the difference of their masses?
A. 0.324 × 10-24 grams
B .1.827 × 10-23 grams
C .1.827 × 10-24 grams
D. 0.324 × 10-23 grams