For the past year, has played tennis a month. now decides to play tennis a month. What does this tell you about 's marginal benefit or marginal cost of tennis? Question content area bottom Part 1 For , _______. A. the marginal cost of a game of tennis must have decreased B. the marginal benefit of a game of tennis must have increased C. either the marginal benefit of a game of tennis has increased or the marginal cost has decreased D. either the marginal cost of a game of tennis has increased or the marginal benefit has decreased