Plants do not have a circulatory system like that of some animals. If a water molecule did "circulate" (that is, go from one point in a plant to another and back in the same day), it would require the activity of
A) only the xylem.
B) only the phloem.
C) only the endodermis.
D) both the xylem and the endodermis.
E) both the xylem and the phloem.
