Concept:Plants depend on soil as the primary reservoir for essential mineral nutrients, which are absorbed by roots after being converted into ionic forms.
Explanation:Soil supplies most of the nutrients required for plant growth, such as potassium, phosphate, and zinc. These nutrients must be in specific ionic forms for root absorption. Soil pH, ideally between 6 and 7.5, affects nutrient availability. Potassium helps roots penetrate deeper to absorb nutrients efficiently. Nutrients like phosphate, potassium, and zinc move mainly through diffusion in the soil. While light and air play roles, they do not directly provide the bulk of mineral nutrients. Chlorophyll is a pigment involved in photosynthesis, not a nutrient source. Therefore, soil is the main nutrient source for plants.
Answer:The correct answer is C. soil.