The correct answer is D) installment plan.
What influenced the rise in consumer spending in the 1920s was the
installment plan.
American people lived a time of prosperity during the 1920s. Indeed, it was such a good time for the American Family that this period was called "the Roaring 1920s". A big reason for people to be able to buy what they wanted was the "installment plans," which were the equivalent of what today we know as buying using credit. That is how people could afford cars and other house commodities.