Final answer:
The property that allows water to move across paper and soak it is capillary action, which is due to adhesion between water molecules and paper fibers.
Step-by-step explanation:
The property of water that causes it to move across paper and soak it when in contact is D. Capillary action. This phenomenon occurs as a result of the adhesion between water molecules and the fibers in the paper. The water 'climbs' against gravity due to the adhesive forces being stronger than the cohesive forces, which allows the water to adhere to the paper fibers. An example of this can be seen when a paper towel absorbs a spill. The liquid is drawn into the porous spaces of the paper towel by adhesion, and the cohesion between the liquid molecules also assists in drawing more of the liquid into the paper.