Question

multiple answer 2 points
eutrophication...
helps to purify water
is a natural process.
is characteristic of lakes with few fish.
happens when fertilizers enter natural waterways.
multiple answer 2 points
impoundments (water reservoirs)...
often help provide electricity to cities.
may disrupt fish migrations.

Explanation:

1. Eutrophication is a natural process accelerated by human - activities like fertilizers entering waterways. It doesn't purify water and isn't specifically characteristic of lakes with few fish.
2. Impoundments can be used for hydro - electricity generation and can disrupt fish migrations due to the barriers they create.

Answer:

1. B. Is a natural process., D. Happens when fertilizers enter natural waterways.
2. A. Often help provide electricity to cities., B. May disrupt fish migrations.