Which of the following statements about the production function F(K,L) = K²L¹/² where K is capital and L is labor, is true? a. The absolute value of the technical rate of substitution increases when K increases. b. Its iso-quants are convex to the origin c. The marginal product of capital is diminishing. d. The marginal product of labor is not diminishing. e. It exhibits constant returns to scale.