I believe the answer is D. Hope this helps ;D
A river that comes from rain, glaicers etc would be a good example of fresh water rivers. Cause the water is coming from something that is most likely been unthouched by man or has been filterd and cleaned from minerals in the ground.
Answer:
What's your question?? sorry
The three substances that cause a double displacement reaction to occur are:
(i) Ionized compounds. These are usually water.
(ii) A gas that bubbles out a solution.
(iii) A precipitate.
In double displacement reaction is where two new compounds are formed when two parts of two compounds switch places. For example; when sodium chloride combines with silver nitrate, the two new compounds formed are Sodium nitrate and silver chloride reason being sodium and silver switched places.