Answer:
A. Consumers purchased too much on credit and were unable to pay back their debts.
Explanation:
While all the factors mentioned in the options might have contributed to the worldwide depression to some extent, the primary cause was the overextension of credit and the inability of consumers to pay back their debts. This situation was further exacerbated by factors such as the stock market crash of 1929, bank failures, and a reduction in international trade due to protectionist policies like tariffs. The Great Depression was a complex event with multiple contributing factors, but excessive consumer debt was a significant catalyst for the economic downturn.