13) Economic efficiency requires that a natural monopolys pricebe a. equal to th

13) Economic efficiency requires that a natural monopolys pricebe a. equal to the lowest price the firm can charge and still makea normal profit. b. equal to average variable cost (AVC) where theAVC curve intersects the demand curve. c. equal to average totalcost (ATC) where the ATC curve intersects the demand curve. d.equal to marginal cost (MC) where the MC curve intersects thedemand curve.