HELP PLS WILL MARK BRAINLY!!!!

A pound of sugar weighs approximately 4.5 × 102 grams. If each grain of sugar weighs 6.25 × 10-4 of a gram, which is the best estimate for the number of grains of sugar in a 5-pound bag?

A.
3.6 × 107 grains
B.
3.6 × 106 grains
C.
3.6 × 108 grains
D.
3.6 × 105 grains