Harry, a Wheat Farmer, Is Deciding Whether or Not to Add

Multiple Choice

Harry, a wheat farmer, is deciding whether or not to add fertilizer to his crops. If he adds 1 pound of fertilizer per acre, the value of the resulting crops rises from $80 to $100 per acre. According to marginal analysis, Harry should add fertilizer if it costs less than

A) $12.50 per pound.
B) $20 per pound.
C) $80 per pound.
D) $100 per pound.