Concept:At field capacity, the soil contains water held against gravity in the pore spaces, and plants absorb this water easily through their roots.
Explanation:After rain or irrigation, excess water drains away downward due to gravity. The water that remains in the soil after this rapid drainage is held by capillary forces in the small pores between soil particles.
This water is known as capillary water, and it is the main form of available water for plant roots at field capacity.
Hygroscopic water is tightly bound to soil particles and is not available to plants.
Gravitational water moves down too quickly or occupies large pores, making it unavailable after drainage.
Superfluous water is an excess amount that is not retained for plant use.
Therefore, the water available for root absorption at field capacity is capillary water.
Answer:A. Capillary water.