Which of the following statements is true? a.) both unicellular and multicellular are at some risk of having too much water entering their cells if they are exposed to water containing no salt. b.) only multicellular organisms have structures that enable them to regulate excess water entering their cells. c.) unicelluar organisms can protect themselves against too much water uptake by enclosing their membrane channels that allow water transport. d.) unicellular organisms, but not multicellular organisms, must deal with the movement of water by osmosis across their cell membranes.