Text: The way to think of the above curves is to begin with a discount, go over to the supply curve to get a volume, and then go up to the postal service cost curve to see how much the postal service saved on the last few pieces that converted to presort.
Entailment: The way to think about the curves above is to start with a discount.
Contradiction: The best way to consider the above curves is by avoiding a discount at all costs.