Steven plans to celebrate his birthday. His ranking is that the first is having buffet dinner in a hotel restaurant; the second is cooking at home; the last is having a hamburger at McDonald's. Having paid HK$500 for buffet dinner, he is allowed to eat whatever amount of food and drinks provided by the hotel restaurant. (16 marks)

a. What is the marginal cost of having one chicken wing in the hotel restaurant? (4 marks)

b. Steven loves chicken wings. He totally ate seven chicken wings and then stopped eating in the hotel restaurant. What would be the marginal benefit of the 10th chicken wing to him? (4 marks)

c. The total benefit of buffet dinner for Steven is exactly equal to HK$500. True or False? (4 marks)

d. How would the cost of buffet dinner change if the water got cut off at home? (i.e., increase, decrease, or no change) (4 marks)