8. Ann's utility function of X and Y is given by U(X, Y) = 4XY. What is Ann's expen- diture function (the minimum amount of money she has to spend to obtain utility u at prices px and py)? (a) E(Pz, Py, u) = PzPyll (b) E(Pz, Py, u) = VPzPy (c) E(Pz, Py, u) = VAPPyu (d) E(Pz, Py, u) = PIPyu2 (e) None of the above