It would be "d. appointment power" that allows him or her to appoint ambassadors, cabinet members, and all military officers, since this is one of the ways in which the president exerts his power over the nation.
Around 200 thousand innocent people died. Around 100 thousand in each bombing. Japan also faced lots of money in property damage, as they had to rebuild. Finally they lost lots of military power.
D. He Wanted to Save Lives
He was warned by his advisors that if he were to try an invade japan it would lengthen the war and cost the lives of many U.S. Troops