The correct answer is Water absorption.
The given figure represents the structure of a root. The root is the structure of the plants, which is embedded in the soil. The main function of the root is to absorb the water and the nutrients from the soil and keep the plant attached to the root. The given figure is a type of tap root, in which a main root and its branches are present. Highly branched root helps in increase in the area of the water and nutrient absorption.