Under "trickle down", additional economic activity will benefit the poor

Which of the following statements is most accurate about the market for call loans:

a. During the 1920s, the supply of loans increased more than the demand. b. During the 1920s, credit was being pulled into the stock market by the rising interest rates on call loans. c. An increased willingness of banks to supply call loans was the decisive factor in causing the bull market. d. The interest rates on call loans decreased significantly during the 1920s.

The socially efficient level of output is determined where

a. marginal social cost equals marginal social benefit b. marginal private cost equals marginal social benefit c. average social cost equals average social benefit d. average private cost equals average social benefit e. total social cost equals total social benefit