Explanation:

- Correct Answer: Option 4 John Maynard Keynes

- John Maynard Keynes is credited with the idea that government fiscal policy can be used as a tool to stabilize the economy, affecting output and employment. His theories, particularly articulated in "The General Theory of Employment, Interest, and Money" (1936), laid the groundwork for what became known as Keynesian economics, advocating for increased government expenditures and lower taxes to stimulate demand during economic downturns.

- Option 1 Frederich Hayek

- Friedrich Hayek was a prominent economist associated with the Austrian School of Economics, known for critiquing centralized economic planning and government intervention, advocating instead for free-market capitalism.

- Option 2 Ludwig von Mises

- Like Hayek, Ludwig von Mises was also a leading figure in the Austrian School. He argued against government intervention, emphasizing the importance of individual choice and free markets in achieving economic efficiency.

- Option 3 Frederic Bastiat

- Frederic Bastiat was a 19th-century French economist known for his ideas on free markets and skepticism about government intervention, particularly focusing on the unseen costs of economic decisions, famously articulated in his work, "The Law."