Concentration of which element is highest in soil

Answer: Option A

The mineral matter of soil is comprised of eight main elements, Oxygen, silicon, Aluminum, Iron, Magnesium, Calcium, Sodium and potassium. Out of these Oxygen is most prevalent on both and volume basis and is the only negatively charged ion, which combines with other cations in different ratios to form different compounds required for the proper growth and development of the plant.