Guttation is the result of Diffusion, Transpiration, Osmosis, Root pressure?

Root pressure is the factor responsible for pulling the sap to rise through a plant stem to the leaves. It occurs in the xylem of some vascular plants, when the soil moisture level is high either at night or when transpiration is low during the day. At night in some plants, root pressure causes guttation or exudation of drops of xylem sap from the tips or edges of leaves. So, the correct answer is option D.