At the XYZ Co., a unit of capital costs 3 times as much as a unit of labor. If the isoquants are convex, and the firm does not change its input mix in the long run, we can conclude that
A)MPK = 3 ∗ MPL.
B)the firm will not hire any capital.
C)the firm will hire 3 times as much labor as capital.
D)the firm will hire 3 times as much capital as labor.