Marvin’s Motors is a monopoly provider of automotive service in the small town of Nowhere. When Marvin reduces his price for oil changes from $25 to $20, he sells 10 additional oil changes per month and his total revenue increases by $40. Which of the following statements is correct?
(A) the output effect is stronger than the price effect
(B) the price effect is stronger than the output effect
(C) Marvin's price is equal to his marginal revenue
(D) Marvin's cost of providing oil changes must have increased