According to Joseph Schumpeter, which of the factors of production is central to economic growth?

Product development is efficient if the

A) new product actually brings great benefits to the consumer. B) producer's marginal cost of product development equals the consumer's marginal benefit. C) producer surplus from selling the product equals the consumer surplus. D) average cost of the product development equals the average revenue generated.

Although some economists believe network externalities are important barriers to entry, other economists disagree because

A) they believe that the dominant positions of firms that are supposedly due to network externalities are to a greater extent the result of economies of scale. B) they believe that most examples of network externalities are really barriers to entry caused by the control of a key resource. C) network externalities are really negative externalities. D) they believe that the dominant positions of firms that are supposedly due to network externalities are to a greater extent the result of the efficiency of firms in offering products that satisfy consumer preferences.