Concept:The tool shown is a soil hydrometer, used to determine the clay content in a soil sample.
Explanation:The soil sample is mixed with water and allowed to settle.
Heavier particles like coarse sand and silt settle down first.
The finest particles, which are clay, remain suspended in the water for a much longer time.
The hydrometer measures the density of this suspension.
This reading helps to estimate the percentage of clay in the soil sample.
Thus, the instrument is used to analyse the clay fraction of the soil.
Answer:A. clay