1. Walmart offers quantity discounts on its family photo holiday cards (cards that it prints with the customer's family photo on it). The price for the first 30 cards is $0.40 per card, and for any additional cards, the price is $0.10 per card. Suppose that Sarah's inverse demand curve for holiday cards is given by P = 0.8 - 0.01Q. How many holiday cards will Sarah purchase?

a. 60.

b. 70.

c. 80

d. 40.

e. 0.