17. Which of the following statements is true? (A)The contents of the phloem are under pressure and the contents of the xylem are under tension. (B) Sieve tube members are empty, dead cells. (C)Vessel element protoplasm is unique because the vacuolar membrane disintegrates, allowing vacuolar water to mix with the cytosol. (D)Phloem sap movement is driven by the atmospheric water potential. (E)Phloem sap moves only short distances, whereas xylem sap moves long distances.