I would think it is "D" but if you think this explanation fits better with another one, then im sorry . . .
Explanation:
President Harry S. Truman, warned by some of his advisers that any attempt to invade Japan would result in horrific American casualties, ordered that the new weapon be used to bring the war to a speedy end. On August 6, 1945, the American bomber Enola Gay dropped a five-ton bomb over the Japanese city of Hiroshima.
The main reason giving for Americas decision to take atomic action is that it was a way to conclude the war without suffering further losses (on the American side at least). There are also those who see the attacks as retribution for Pearl Harbor and the many American lives lost in bloody warfare with Japan.
