Which of the Following Supports the Finding That Sugar Translocation

Multiple Choice

Which of the following supports the finding that sugar translocation in phloem is an active (energy-requiring) process?

A) Sucrose occurs in higher concentrations in companion cells than in the mesophyll cells where it is produced.
B) Movement of water occurs from xylem to phloem and back again.
C) Strong pH differences exist between the cytoplasm of the companion cell and the mesophyll cell.
D) H⁺-ATPases are abundant in the plasma membranes of the mesophyll cells.
E) All of the above apply.