The correct option is D Root pressure
Various ions from the soil are actively transported into the cells of roots. Water follows its potential gradient and enters the roots. This increases the hydrostatic pressure in the root xylem. This pressure is called root pressure. In some herbaceous plants, in the night, the stomata are closed and transpiration is low. The root pressure pushes up excess water to the leaves. This water collects as droplets near the tips of the leaves. This is called guttation.