(Figure: Corn and Oil in the United States and the United

(Figure: Corn and Oil in the United States and the United Kingdom) Refer to the graphs for the United States and the United Kingdom. If the starting point is a, what is the opportunity cost of the United Kingdom producing one more barrel of oil?

A) 0.5 bushel of corn
B) 1 bushel of corn
C) 1.5 bushels of corn
D) 2 bushels of corn