Factor that contributes the most to the process of water erosion is Evaporation. The correct option is A.
What is evaporation?
Evaporation is the phenomenon of converting the liquid into gas phase by the addition of heat energy.
Erosion is also a natural phenomenon. Trees and plants hold soil in place and prevents the soil erosion. Just like that, the water erosion happens when more than natural evaporation happens due to increased heat by various factors.
Thus, Evaporation contributes the most to the process of water erosion. The correct option is A.