Additional Fertilizer per Acre (gallons) At what point is the marginal benefit of applying additional fertilizer no longer greater than the marginal cost of the fertilizer?
A.3 gallons
B. 4 gallons
c. 5 gallons
D. 6 gallons
E. 7 gallons

B. 4 gallons

Explanation:

Up until the 4th gallon of fertilizer added, the cotton harvested had increased by more than 1 ton for every gallon added. After the 4th gallon was added though, the Cotton harvested stayed the same regardless of how much more gallons were added. At the 4th gallon therefore Marginal benefit of gaining more tons of cotton stopped being greater than the additional gallon of fertilizer added.

d) iowa i believe is the answer