What happens to the plants used in phytomining after they have absorbed metal compounds?

The correct option is They are burned to produce ash containing metals. This answer is correct because it matches the approved learning objective to describe phytomining as using plants to absorb metal compounds from soil. (HT only) in the subtopic Alternative methods of extracting metals.

The correct option is They are burned to produce ash containing metals. They are burned to produce ash containing metals is correct because it directly supports the approved learning objective to describe phytomining as using plants to absorb metal compounds from soil. (HT only). This belongs to the subtopic Alternative methods of extracting metals within Using the Earth's resources and obtaining potable water, so the explanation must stay tied to that curriculum context. The other options are incorrect because they either do not answer this learning objective, use a vague statement, or move away from Alternative methods of extracting metals.