Who was the economist who first proposed that governments use taxes and subsidies to correct for externalities?

In a small economy in 2016, aggregate expenditure was $850 million while GDP that year was $800 million. Which of the following can explain the difference between aggregate expenditure and GDP that year?

A) Aggregate expenditure is always less than GDP in developing countries. B) Aggregate expenditure is always less than GDP in developed countries. C) Firm investment in inventories was less than anticipated in 2016. D) Firm investment in inventories was greater than anticipated in 2016.

Beginning from full-employment equilibrium, illustrate graphically how each of the following would impact the economy

a. the short-run impact of an unanticipated decrease in the money supply b. the long-run impact of an unanticipated decrease in the money supply