q23 and q24 please..thank you

23. In perfect competition firms set price equal to price. Why can't firms do this when there are internal economies of scale? Internal economies of scale imply that the firm can create entry barriers by setting the price lower than marginal cost. To keep competitor out of the market , the firm charges a price less than marginal cost. b, internal economies of scale imply decreasing average cost as output rises which also implies that marginal cost is less than average cost. If price is set equal to marginal cost, the firm will be making a loss. c. Internal economies of scale arise when the cost per unit falls as the industry grows larger, In this case the number of firms in the industry increases along with the firm's ability to set a price higher than marginal cost . d. This statement is not correct. Firms operating under internal economies of scale set price equal to marginal cost. 24. Under the model of monopolistic competition, a( an) in the number of firms in the industry will cause to a. increase; average price; decrease b. increase; marginal cost; decrease c. increase; average price; increase d. increase; average cost; decrease e. decrease, markup, decrease