The figure is drawn for a monopolistically competitive firm. A graph of Price versus Quantity shows a straight line, M R, decreasing linearly, a second straight line, Demand, decreasing linearly above M R and at a slightly slower rate, a third straight line, M C, increasing linearly, and a curved line, A T C, decreasing at the beginning and increasing at the end. At Q = 100, M C = M R at $90, and this line hits the demand curve at $140 and the A T C curve at $160. At Q = 133.33, the value of M R is $56.67, and Demand = M C at $123.33. Q = 154.92 hits a point where M C = A T C. Refer to Figure 17-6. Efficient scale is reached a. between 133.33 units and 154.92 units. b. at 100 units. c. at 133.33 units. d. at 154.92 units