Answer:
Option C=> John Maynard Keynes.
Step-by-step explanation:
The "General theory of employment, interest, and money" was first published in the year 1936 and was authored by John Maynard Keynes. Apart from the book ''general theory of employment, interest, and money", John Maynard Keynes also wrote another book titled " A Treatise on money".
Apart from what was given in the question that is "that large-scale government deficit spending was appropriate during economic downturns" John Maynard Keynes also made sure to explain the reason capitalism can not produces a stable economy. Generally, his book was on how the economy can be stable.