Wendy retails motor homes, which she buys for a sum that does not vary with the number she purchases from the manufacturer. She can sell eleven per week at $40,000. If she limits sales to ten, she can charge $41,000 each. She will sell eleven per week if the cost of each vehicle is no more than
a. $41,000.
b. $30,000.
c. $20,000.
d. $40,000.