Suppose That Firms a and B Are Cournot Duopolists in the Salt

Multiple Choice

Suppose that firms A and B are Cournot duopolists in the salt industry. The market demand curve can be specified $P = 200 - Q _ { A } - Q _ { B }$ The marginal cost to each firm is $40. Suppose that firm A is producing 100 units. What is firm B's profit-maximizing quantity?

A) 100.
B) 60.
C) 30.
D) 20.