James Richards and Martyn Caldwell conducted an experiment to test the hypothesis that hydraulic lift occurs in Artemisia tridentata, a species of sagebrush common in the western United States. Each plant in the experimental group was covered with an opaque plastic bag for more than two days to prevent photosynthesis and greatly reduce transpiration, and control plants were left uncovered. Fluctuations in soil water potential were measured, and other aspects of the experimental systems were observed. Which of the following observations from such an experiment provides the strongest support for the occurrence of hydraulic lift in A. tridentata?
A) finding, in the experimental plants, that the water potential of upper roots is greater than that of the leaves
B) finding, in the experimental plants, that the water potential of the lower roots is greater than that of the upper roots
C) finding, in the experimental plants, that the water potential of the lower roots is less than that of the upper roots
D) finding that the shallow soil beneath the experimental plants is drier than beneath the control plants
E) finding that the shallow soil beneath the experimental plants is moister than beneath the control plants
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