A firm currently has the following production (marginal products) and input price situation with respect to two types of labor (L1 and L2) which can be imperfectly substituted for one another: MPL1 = 10; PL1 = 15; MPL2 =4; PL2 = 2. The firm is currently operating in the second stage of the production function with respect to each type of labor. If the firm wishes to minimize cost for the current output, it should:?  A.Make no change. B.Increase L2 and decrease L1. C.Increase L1 and decrease L2. D.Increase both inputs. E.Decrease both inputs.