Assume that prior to the imposition of an importation fee the country annually consumed $900$ million short tons of coal, all domestically mined at a price of $$66$ per short ton. How would the cost benefit analysis of the import fee change if$,$ after imposition of the import fee, the following circumstances are assumed to result from energy consumers switching from crude to coal?

a$.$ Annual consumption of coal rises by $40$ million short tons but the price of coal remains unchanged.

b$.$ Annual consumption of coal rises by $40$ millions short tons and the price of coal rises to $$69$ per short ton. In answering this question, assume that the prices of other goods, including coal, were not held constant in eliminating the demand schedule for crude oil.

c$.$ Annual consumption of coal rises by $40$ million short tons and the price of coal rises to $$69$ per short ton. In answering this question, assume that the prices of other goods, including coal, were not held constant in eliminating the demand schedule for crude oil.

d$.$ The market price of coal underestimates its marginal cost by $$7$ per short ton because the coal mined in the country has a high sulfur content that produces smog when burned. In answering this question, assume that the annual consumption of coal rises by $40$ million tons, but the price of coal remains unchanged.