• Warren Harding • Calvin Coolidge • Herbert Hoover How did the presidents above contribute to the prosperity of the 1920s? A. They opened new markets for American products overseas by employing "dollar diplomacy." B. They invested large sums of American tax dollars giving incentives to business owners. C. They carried the ideals of the Progressive era into the 1920s and regulated industry. D. They were largely inactive and allowed businesses to grow unregulated.