Concept:Soil water that remains in the soil after excess water drains and is not tightly bound to particles.Explanation:Water in soil exists mainly as gravitational, capillary, and hygroscopic water.Gravitational water moves down quickly under gravity and is not easily absorbed.Hygroscopic water is held as a thin film around soil particles and is too tightly bound for roots to take up.Capillary water is retained in the small spaces between soil particles by surface tension.This capillary water is the main source available to plant roots for absorption.Answer:A. capillary water