A representative firm with short-run total cost given by TC = 50 + 2q + 2q2 operates in a competitive industry where the short-run market demand and supply curves are given by QD = 1,410 - 40P and QS = -390 + 20P. Its short-run profit-maximizing level of output is:
a. 0 units.
b. 1 unit.
c. 2 units.
d. 5 units.
e. 7 units.