In Seawater,Mg²⁺ Is About 1350 Mg Mg²⁺/L

Multiple Choice

In seawater,Mg²⁺ is about 1350 mg Mg²⁺/L.How many grams of magnesium are in a pool that is 25 ft by 12 ft by 6 ft? (1 ft = 12 inches and 1 inch = 2.54 cm)

A) 4.78 × 10^{2 g}
B) 74.1 g
C) 6.88 × 10^{4 g}
D) 6.88 × 10^{7 g}
E) 1.64 × 10^{3 g}