Monopolists are able to practice price discrimination because

A. they have constant marginal cost.

B. of differing price elasticities of supply.

C. they have a constant average cost.

D. of differing average willingness-to-pay among consumers.

Monopolists can practice price discrimination because of D. different average willingness to pay among consumers.

Since monopolies have a unique product and no competitors, they can price the product wherever they wish. If they can separate consumers into groups that have different elasticities of demand, they can price discriminate. A good example is a golf course that charges senior citizens a lower price to play on days other than the weekend. Senior citizens can not afford the weekend rates and are available to play on weekdays, while the younger golfer may be working on weekdays and must pay the higher rate.