Barriers to entering an industry:a. apply only to purely monopolistic industries. b. encourage allocative efficiency. c. encourage productive efficiency. d. are the basis for monopoly.

d. are the basis for monopoly.

Explanation:

Barriers to entering an industry are the basis for monopoly. When the monopolistic government tries to impose barriers and regulations that work against the industries, then it becomes hard. Usually the high initial fixed cost, taxes, high labor costs are one of the reason that form the barriers for entering the industry.

These are some of the obstacles that prevent new competitors to enter the industry.