John maynard keynes developed new economic theories in response to the

a. stock market crash of 1929.

b. great depression of the 1930s.

c. first and second world wars.

d. economic boom of the 1950s.

The answer is B. Great Depression of the 1930s.

Explanation:

Keynesian economics is an economic theory of total spending in the economy and its effects on output and inflation. Keynesian economics was developed by the British economist John Maynard Keynes during the 1930s in an attempt to understand the Great Depression. Keynes advocated for increased government expenditures and lower taxes to stimulate demand and pull the global economy out of the depression.

some american cities felt workers were being oppressed by business monopolies