C. Avoid the problem of fighting Allied powers on two fronts; In more detail, the Schlieffen plan was the Imperial German plan to force a French surrender early in the case of a two front war with France and Russia. The plan stated that German troops should attack the French lowlands by marching through Belgium and advancing along the coast until the German units completed a pincer movement to the west of Paris, cutting off the main French force from their Capital. This was planned to be done in a few weeks, that way Germany could start an offensive against Russia before they could mobilize their army.
He chose to bomb Hiroshima because the other option of invading japan would lead to more bloodshed than the bomb itself could do.
it was also used to weaken their industries in Hiroshima and strong-arm the japanese into surrendering.
hope this helped a little