A Large Firm That Is a Price Leader in an Industry

Multiple Choice

A large firm that is a price leader in an industry characterized also by many small competing firms estimates that the market demand for its product to be as follows: Q_m = 20,700 - 75P, where Q_m is units per month.
It expects small firms in the industry to supply output according to the following function: Q_s = 700 + 25P. What is the demand function for the large firm?

A) Q_L = 20,000 - 100P.
B) Q_L = 20,000 + 100P
C) Q_L = 20,700 + 125P
D) Q_L = 21,400 - 100P
E) Q_L = 21,400 + 100P