Figure 19-1 A graph of Q versus L shows a curved line, increasing from left to right from the origin and through the following points. (1, 120), (2, 210), (3, 285), (4, 345), (5, 390), and (6, 420). Refer to Figure 19-1. Suppose the firm sells its output for $12 per unit, and it pays each of its workers $700 per week. How many workers will the firm hire to maximize its profit? a. 4 b. 5 c. 2 d. 3