Answer: Cell division.
Explanation: Cell division is responsible for the growth of roots in the plant. The growth in the roots of the plant is ultimately the growth of the whole plant.
Roots are very important as it helps in absorption of the nutrients and water from the soil for the growth and development of the whole plant.
The cell division in the plant body leads to the development of the roots, that is found in the soil providing the support to the plant to stand straight in the soil.
