Kate and Alice Are Small-Town Ready-Mix Concrete Duopolists

Kate and Alice are small-town ready-mix concrete duopolists. The market demand function is where P is the price of a cubic yard of concrete and Q^d is the number of cubic yards demanded per year. Marginal cost is $80 per cubic yard. Suppose Kate enters the market first and chooses her output before Alice. What is Alice's profit?

A) $10,000
B) $5,000
C) $20,000
D) $15,000