Based on the information given, indicate whether the following industry is best characterized by the model of perfect competition, monopoly, monopolistic competition, or oligopoly. a. industry a has a four-firm concentration ratio of 0.005 percent and a herfindahl-hirschman index of 75. a representative firm has a lerner index of 0.45 and a rothschild index of 0.34. b. industry b has a four-firm concentration ratio of 0.0001 percent and herfindahl-hirschman index of 55. a representative firm has a lerner index of 0.0034 and rothschild index of 0.00023. c. industry c has a four-firm concentration ratio of 100 percent and herfindahl-hirschman index of 10,000. a representative firm has a lerner index of 0.4 and rothschild index of 1.0. d. industry d has a four-firm concentration ratio of 0.0001 percent and herfindahl-hirschman index of 5,573. a representative firm has a lerner index of 0.43 and rothschild index of 0.76