type of soil and salinity nitrate levels and turbidity human consumption and pH natural disasters and tidal changes
I gave my students this multiple choice question: Which factors can have the greatest effect on the health of a river system?

Only one answer is correct among these 4 choices:
- type of soil and salinity
- nitrate levels and turbidity
- human consumption and pH
- natural disasters and tidal changes

Could you tell me which one is correct?

nitrate levels and turbidity