The figure given below shows the market for shoes in the U.S. The domestic price line with tariff lies above the international price line. D d and S d are the domestic demand and supply curves of shoes respectively. D d S d World price Domestic price with tariff Quantity D 1 S 1 D 0 a b c d S 0 Price 0 T he tariff revenue of the U.S. government is shown by area _____ . a. a b. ( a + b ) c. c d. ( b + c + d )