Multiple choice

Which situation is a result of human activities?

  1. decay of leaves in a forest adds to soil fertility

  2. acid rain in an area kills fish in a lake

  3. ecological succession

  4. natural selection on an island changes gene frequencies

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Acid rain is primarily caused by industrial emissions (sulfur dioxide and nitrogen oxides) resulting from human activity, which then damages aquatic ecosystems.