Which letter in the diagram corresponds to phytoextraction?

Phytoextraction

A method of removing contaminants from soil, water, or air involving the use of plants that can absorb and concentrate pollutants in their biomass.

Diagram

A simplified drawing or plan that represents information or an idea in a clear and concise manner.

Contaminants

Substances that cause pollution or impurity in another substance, often harmful to health or the environment when present at high levels.