Suppose that the production function is Y = 9 K⁰.⁵/⁰.⁵ With this production function, the marginal product of labor is MPN = 4.5 K⁰.⁵/N⁰.⁵ The labor supply curve is NS = 85x[(1 – t) xw]², where w is the real wage rate, t is the tax rate on labor income, and hence (1 – t) x W is the after-tax real wage rate. The capital stock is K = 25. Assume that the tax rate on labor income, t, equals zero.

Which of the following equations represents the labor demand curve?
A. ND = 112.5/w²
B. ND = 45/ N⁰.⁵
C. ND = 125/w
D. ND = 506.25/w²
E. ND = 125 x N⁰.⁵