TOEFL Listening: TPO-TOEFL听力TPO - H62Q1M9M839K57MBR$

What can be inferred about the professor 's view on phosphorus getting washed into rivers? A. She is unconcerned because phosphorus is a beneficial nutrient B. She is concerned about the quantity of phosphorus entering the waterways C. She thinks that the amount of research conducted on the topic is excessive D. She is frustrated that most of her students are unaware of the phenomenon