Unification was the most significant in helping Germany become rapidly industrialized. Option D is correct.
In 1871, Prussia finally united Germany. It then marked the new phase of Germany's industrial revolution.
Furthermore, the provinces of Alsace and Lorraine that Germany took from France provided Germany even further natural resources which were vital for industrialization. Heavy industry increased and developed after the German Unification.
The great depression was started shortly after the stock market crash on october in 1929 it sent wall street into a spiraling panic and destroyed millions of investers
