Answer:
Hey there!
I believe that David's prediction would be: If the amount of pollutants in the atmosphere reached an amount unhealthy for the salamanders, then the salamander population would decrease.
Let me know if this helps :)
Answer: Is a group of organisms of the same species that interbreed for example a group of robins in North America
Answer: I would say its probably A I'm not sure but that might be it
Explanation:
1. compound
2. element
3. element
4. compound
elements are only one type of thing, compounds are more than one type of thing