The correct answer is letter D. Rain forests are not a type of ecosystem that the governor of a US state would cover under the US Clean Water Act.
This act emphasizes the importance of preserving and conserving the surrounding bodies of water of US. It regulates the pollutant discharges of materials into the water of the United States and ensures the proper conservation of such water forms.
A rain forest is not a water form, but a rather a land form, hence it is not included in the act, and is included in other regulations stated by the US government.