The correct answer is: C. J. M. Keynes.
A mixed economy is an economic system that combines elements of both capitalism and socialism. In a mixed economy, some of the means of production are privately owned and operated, while others are owned and operated by the state. The government plays a role in regulating the economy and providing social welfare programs.
J. M. Keynes was a British economist who is considered one of the most influential economists of the 20th century. He is best known for his work on macroeconomics, which is the study of the economy as a whole. Keynes argued that the government should play an active role in managing the economy, and he developed a number of economic theories that are still used today.
Karl Marx was a German philosopher, economist, and social theorist who is best known for his work on communism. He argued that the history of all hitherto existing society is the history of class struggles. He believed that the capitalist system would eventually collapse due to its own internal contradictions, and that a communist society would emerge in its place.
Adam Smith was a Scottish economist and philosopher who is considered the father of modern economics. He is best known for his work on capitalism, which he described in his book The Wealth of Nations. Smith argued that the free market is the best way to organize an economy, and that government intervention should be limited.
Alfred Marshall was an English economist who is considered one of the founders of neoclassical economics. He is best known for his book Principles of Economics, which is considered one of the most important works in the history of economics. Marshall argued that the economy is a complex system, and that it is important to study the interactions between different parts of the economy.