The correct answer is A) eliminating the ability to buy on credit.
The condition that did NOT contribute to the consumer economy of the 1920s was "eliminating the ability to buy on credit."
It was totally the opposite. It was the ability to buy on credit which made people started a consumerist behavior purchasing so many things, needed or not during that time. Indeed, those years received the name of "the Roaring 1920s," because it was a time of good economy in the United States, which people used to buy things on credit.