Suppose a firm is producing at a point where its marginal product of labor (MP) is 12 and its marginal product of capital (MPK) is 18. The wage (w) is 4 and the rent (r) is 3. Thus, A. The firm should not change how much it spends on capital and labor. B. The firm should spend less on capital and more on labor. C. The firm should spend more on capital and less on labor. D. It is impossible to tell with the given information.