Final answer:
The Glass-Steagall Act separated commercial banking, investment banking, and insurance into three separate industries...
Step-by-step explanation:
The act that separated commercial banking, investment banking, and insurance into three separate industries was the Glass-Steagall Act. This act, also known as the Banking Act of 1933, was signed into law by President Franklin D. Roosevelt in response to the financial crisis of the Great Depression.
It prohibited banks from engaging in both commercial and investment banking activities and established the Federal Deposit Insurance Corporation (FDIC) to insure bank deposits. The Glass-Steagall Act aimed to prevent conflicts of interest and protect the stability of the banking system.