1.different groups of customers different prices for the same products. This is the correct answer. Third-degree price discrimination (aka “market segmentation”) is the practice of charging different groups of customers different prices for the same products. 2.second-degree price discrimination. This is the correct answer. Indeed, quantity discounts are an example of second-degree price discrimination. 3.third-degree price discrimination. This is the correct answer. Charging different prices to members of different groups with different demand curves (aka “market segmentation”) is third-degree price discrimination. 4.the demand curve and the marginal revenue curve are identical. This is the correct answer. In fact, with perfect price discrimination the firm charges a price for each unit equal to consumer’s maximum willingness to pay for that unit, and that consumers’ willingness to pay is represented by the (inverse) demand curve. This implies that P = MR and that the marginal revenue curve coincides with the demand curve.