Hal Cooper is given an injection of a particular drug at noon, and samples of blood are taken at regular intervals to determine the concentration of drug in his system. It is found that the concentration increases at an increasing rate with respect to time until 1 P.M., and for the next 3 hours, continues to increase but at a decreasing rate until the peak concentration is reached at 4 P.M. The concentration then decreases at a decreasing rate until 5 P.M., after which it decreases at an increasing rate toward zero. Sketch a possible graph for the concentration of drug C(t) as a function of time.