Use the Following to Answer Questions

Multiple Choice

Use the following to answer questions :
Figure: Sugar and Freight Trains
-(Figure: Sugar and Freight Trains) Look at the figure Sugar and Freight Trains. Suppose the economy is operating at point C. The opportunity cost of producing the fourth freight train would be:

A) 19 tons of sugar.
B) 45 tons of sugar.
C) 80 tons of sugar.
D) 3 freight trains.