Final answer:
Without specific information on solute concentrations, we cannot definitively say whether water would move into or out of the potato cells in tube A; it depends on the relative concentrations inside and outside the cells, following the principle of osmosis.
Step-by-step explanation:
Water moves according to the water potential gradient, which is influenced by factors such as solutes, pressure, and gravity. In the context of the potato cells in tube A, we must consider osmosis, which is the diffusion of water through a semipermeable membrane. If tube A has a higher concentration of solutes inside the potato cells compared to the outside solution, it is indicated as a hypertonic solution and water would move out of the potato cells. Conversely, if the outside solution has a higher solute concentration, known as a hypotonic solution, water would move into the potato cells. However, without specific information about the solute concentrations in tube A compared to the potato cells, we cannot definitively complete the sentence. A general statement based on the principles of osmosis would be: 'Water would move into or out of the potato cells in tube A, depending on the relative solute concentrations.'