63. REACTION TO MEDICATION In certain biological models, the human body's reaction to a particular kind of medication is measured by a function of the form 1 F(M)=(kM2 M3) OEMEk where k is a positive constant and M is the amount of medication absorbed in the blood. The sensitivity of the body to the medication is measured by the derivative S = F '(M). a. Show that the body is most sensitive to the med- . . k ication when M = g