Correct option is B
In deep soil, the soil profile is generally studied up to a depth of 150 cm. This depth allows for the examination of the various layers of the soil, including the surface, subsoil, and underlying layers that are important for plant growth and root development.
This depth covers the topsoil and subsoil, which are vital for crop growth.
Soil characteristics at this depth help in assessing the soil's fertility, water retention, and root penetration.