11. T F The marginal-cost curve that is above the average-variable-cost curve is the competitive firm's short-run supply curve. 12. T F The purely competitive firm's demand curve slopes downward. 13. T F The break-even point and the shut down point are the same. 14. T F For a purely competitive firm D = AR = MR = P because that firm is a price taker charging only what the market dictates. 15. T F When a firm produces no output, fixed costs are zero in the short run