Explanation:

Here's a quick breakdown of the options and relevant statements:

- Option 1: Adam Smith

- Known as the father of modern economics.

- Famous for his work "The Wealth of Nations."

- Did not develop the theory of opportunity cost.

- Option 2: Gottfried Haberler

- An Austrian economist.

- Known for his contributions to international trade theory.

- Provided significant insights into opportunity cost.

- Option 3: Milton Friedman

- An influential American economist.

- Known for his work on monetarism.

- Did not provide the theory of opportunity cost.

- Option 4: John Keynes

- Developed Keynesian economics.

- Known for his work on employment and economic policies.

- Did not provided the theory of opportunity cost.