Meera can sell 1 jacket for $40, 2 jackets for $35 each, 3 jackets for $30 each, 4 jackets for $25 each, and 5 jackets for $20 each. Her marginal cost of production is constant at $20 for each additional unit (or jacket) produced. If she behaves like a monopolist, what is the number of jackets she will sell?
a. 1
b. 3
c. 4
d. 5