Keynes argued that a. monopolistic elements in the economy will prevent an immediate sharp fall in prices as a result of decreasing demand. b. supply creates its own demand. c. prices are flexible in a downward direction. d. wages are flexible in a downward direction.

a. monopolistic elements in the economy will prevent an immediate sharp fall in prices as a result of decreasing demand

Explanation:

When there is recession the price of the factor goes down and with that, the insufficient demand for a certain good or services is eliminated. The reasoning is that the decrease in prices stimulates demand and adjust the market.

Keynes among other economist consider that unemployment increase during recessions because the nominal wages rate do not fall. As the union and worker do not want to see their wage decrease. Same is applied to prices which makes then inflexible in a downward direction.

While "supply creates its own demand" is "Says's Law" which is rejected in keynes main book "The general theory"

Hece option A is the only one which is true