Suppose a Firm Hires Both Labor (L) and Capital (C) $\mathrm { MP }_ { C } = \mathrm { MP }_ { L } = P _ { X }$

Multiple Choice

Suppose a firm hires both labor (L) and capital (C) under purely competitive conditions. The price of labor is P_L, and that of capital is P_C. The marginal product of labor is MP_L, and that of capital is MP_C. The firm sells its product competitively at a price of P_X. Which of the following must pertain if the firm is to minimize the cost of producing any output?

A) $\mathrm { MP }_ { C } = \mathrm { MP }_ { L } = P _ { X }$
B) $\mathrm{MPC}_{C}=P_{C} \text { and } \mathrm{MP}_{L}=P_{L}$
C) $\mathrm{MP} _{C} / P_{C}=\mathrm{MP}_{L} / P_{L}$
D) $\mathrm { MP } _{C} / P _{X} = M \mathrm { MP } _ { L } / P _{X}$