Which of the following statements is correct?

a. The monopolist will maximize profit by

producing at that point on the demand curve

where elasticity is zero

b. In seeking the profit maximizing output, the

monopolist under allocates resources to its

production

c. The monopolist maximizes profits by producing

that output at which the differential between price

and average cost is the greatest

d. Purely monopolistic sellers earn only normal

profits in the long run