How did von Bismarck manage to defeat France and ultimately form the German nation he envisioned? What key tool did he use?

Count Helmuth von Moltke directed German troops through France, much like his nephew Moltke who did the same during World War I. ... Bismarck used diplomacy and political manipulation to keep Italy, Russia, and Britain out of the war, isolating France. Schlieffen Plan, battle plan first proposed in 1905 by Alfred, Graf (count) von Schlieffen, chief of the German general staff, that was designed to allow Germany to wage a successful two-front war. The plan was heavily modified by Schlieffen’s successor, Helmuth von Moltke, prior to and during its implementation in World War I. Moltke’s changes, which included a reduction in the size of the attacking army, were blamed for Germany’s failure to win a quick victory.

Explanation:

the right answer is d