The correct answer is D. Guttation.
Guttation is the exudation of drops of water from hydathodes, which are specialized pores on the undersides of leaves. It occurs when the water pressure in the xylem exceeds the atmospheric pressure, and is most common in plants that are growing rapidly or in humid conditions.
Root pressure is the upward movement of water and dissolved minerals from the roots to the leaves. It is caused by the active transport of ions out of the root cells, which creates a negative pressure gradient that draws water up from the soil.
Transpiration is the loss of water vapor from the leaves of plants. It is a necessary process for plants, as it helps to cool them and to transport nutrients from the roots to the leaves. Transpiration is driven by the difference in water vapor pressure between the air and the leaf surfaces.
Osmotic pressure is the pressure that must be applied to a solution to prevent the movement of water across a semipermeable membrane. It is caused by the difference in the concentration of solutes on either side of the membrane.