Franklin D. Roosevelt (FDR) often placed much of the blame for causing the Great Depression on bankers, stockbrokers, and big business owners. While he also criticized the policies of the federal government and former president Herbert Hoover, his rhetoric frequently focused on the need for reform and regulation of the financial system and large corporations to prevent future economic crises. Therefore, the most accurate answer would be:
• on bankers, stockbrokers, and big business owners.