For questions 9 - 10 use the following information. A charity is planning to hold a pancake breakfast. Demand comes from two sources: "adults" (defined as people less than 60 years old) and "seniors" (defined as people 60 years old or older). The demand equations of the two groups are: PA = 18 - QA + QA = 90 -5 . PA Ps = 14 -Q5 4 Qs = 140 - 10 . PS The charity can charge a different price for adults and seniors the people selling tickets will ask to see identification from anyone who is not clearly above or below 60 years old. The marginal cost per adult is $2.80, but the marginal cost per senior is only $2 because they tend to eat less. The venue, which has been donated to the charity, cannot accommodate more than 100 total people (adults plus seniors). 9. What is the optimal senior citizen discount? That is, if you calculate the profit-maximizing prices for adults and seniors, how much lower is the price for seniors relative to the price for adults? A. $2.40 B. $2.60 C. $2.80 D. $3.00 E. none of the above is the optimal senior citizen discount