Tree A is 5 meters tall, and tree B is 10 meters tall. Which tree has to expend more energy to move water up the trunk due to cohesion- tension and transpiration? An aphid attaches itself to the surface of a stem and pierces the stem with its mouthpart, called a stylet. A droplet of clear, sugary liquid exudes from the back end of the aphid. How can this be explained? A. The aphid's stylet has tapped into xylem, and pressure from the xylem forced water out of the aphid's body. B. The aphid is extracting water from the vascular tissue in A. Tree A . Tree B C. Both trees expend the same number of calories, since energy used in pumping water up the trunk in a tree is constant. the stem. C. The aphid is extracting sugar water from the xylem. D. The aphid's stylet has tapped into phloem, and the pressure from the phloem forced sugar water out of the aphid's body. D. Both trees expend virtually no energy, since water movement up the trunk of a tree is driven by evaporation of water from leaves.