This graph shows the increase in fertilizer and the resulting change in yield for a cotton farm. A line graph has additional fertilizer per acre in gallons along the x-axis with values ranging from 1 to 7 in increments of 1, and cotton harvested in tons along the y-axis with values ranging from 10 to 70 in increments of 10. 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