The correct answer is option 3 - John Maynard Keynes.

Adam Smith, a Scottish economist, is known as the father of modern economics and wrote extensively on topics such as the division of labor and the invisible hand. However, he did not specifically coin the concept of the "Paradox of Thrift".

Alfred Marshall, an English economist, is known for his influential work "Principles of Economics". While he discussed the concept of saving and consumption, he did not explicitly formulate the Paradox of Thrift.

The Paradox of Thrift was actually coined by John Maynard Keynes, a British economist, in his book "The General Theory of Employment, Interest, and Money" published in 1936. Keynes argued that during periods of economic downturn, when individuals try to save more by reducing their consumption, it can have a negative impact on the overall economy. This is because reduced consumption leads to decrease in demand, which in turn can lead to lower production, job cuts, and ultimately worsen the economic situation.

Alert - The provided answer is correct.