Final answer:
The solubility of a material is the key property that allows for the easy removal of an inscription with water, as it refers to the material's ability to dissolve in a solvent.
Step-by-step explanation:
The property of the material that allows for the easy removal of an inscription with water is solubility. This is because solubility refers to the ability of a substance to dissolve in a solvent, in this case, water. When the inscription material is soluble in water, it can easily dissolve when water is applied, leading to its removal.
Other properties like adhesion, hardness, and viscosity do not directly relate to the substance's ability to dissolve in a solvent, which is essential for the inscription to be easily wiped away with water.
Adhesion does play a role in the process by allowing water molecules to bond to the material, but it is the solubility that is the key factor in the removal. Just as adhesion allows water to move up a plant due to capillary action, solubility facilitates the dissolving of substances in water.