Which of the following is not evidence supporting the hypothesis that sugar translocation in phloem (phloem loading) is an active (energy-requiring) process? A. Sucrose occurs in higher concentrations in phloem companion cells than in the leaf cells where it is produced. B. Movement of water occurs from xylem to phloem and back again. C. Large pH differences exist between the interior and exterior of phloem companion cells. D. Strong charge differences exist between the interior and exterior of phloem companion cells. E. H+-ATPases are abundant in the plasma membranes of phloem companion cells.