The correct option is C Hygroscopic water
In a fully watered field, the water, which is held between the soil particles is available to the plants and is called as capillary water. The gravitational water is the water, that has entered the water table and is not available to the plants. The run away water is the water, which has been lost as surface run away and is not available to plants. The hygroscopic water is the water, which is present as a thin film around the soil particles and is not available to the plants.