Answer
When a monopolist switches from charging a single price to perfect price discrimination, it reduces:
c) consumer surplus
Work Step by Step
If a monopoly were to charge a single price for a good, people willing to pay more for that good wouldn't have to do so, because of the same price charged for all customers. This is called the consumer surplus.
If a monopoly were to practice perfect price discrimination, however, then every customer would pay exactly what they are willing to pay for the good and nothing less. In this case, the consumer surplus would be reduced.
