37. The Expensive Winos is a wine distributor that has the exclusive rights to retail the whole catalog of wines from a famous Oregon vineyard.The distributor sells the wine at marginal cost, which is an extremely attractive price as it involves zero mark-up per bottle. However, customers must essentially obtain the right to buy at those prices by first purchasing a membership to Winos Groupies, a loyalty program run by the company.This is most likely an example of:

a. Economies of scale that create the conditions for a natural monopoly.

b. Segmented price discrimination.

c. Bundling.

d. A two-part tariff used by a firm with market power to extract consumer surplus.