Concept:Soil aeration means the presence of air in the soil. Removing excess water from soil improves air circulation.Explanation:Poor soil aeration is often caused by waterlogged or overly wet soil.Irrigation adds more water, making aeration worse.Mulching and fertilizer application do not directly remove excess water from the soil.Soil drainage removes excess water, allowing air to enter the soil and improving aeration.Answer:C. soil drainage