How did the franco-prussian war of 1870—1871 contribute to german unification?

german victory in the war increased nationalism and patriotism in germany.
french victory in the war united the germans against a common enemy.
the war resulted in wilhelm i becoming king of prussia.
the war showed that only military force could unite germany.

"German victory in the war increased nationalism and patriotism in Germany."

Explanation:

The Franco-Prussian War was the most important conflict that was fought in Europe after the Napoleonic wars and before the First World War and ended with the complete victory of Prussia and its allies. The most important consequence was the creation of the German Empire, which maintained a very influential role in the international political relations of the following decades. The French debacle also brought the end of the Second Empire of Napoleon III and, with the fall of it, the temporary subordination of the role of France in comparison with the other powers of European families. The end of the imperial era in France marked the beginning of the Third French Republic, which - in size and influence - became the most important republican regime among those then existing on the continent.

a.) are both appointed for life