human
Question: One of the principal causes of acid rain is

Choices:
A) waste acid from chemical factories being pumped into rivers
B) acid from chemical laboratories evaporating into the air
C) gases from burning coal and oil dissolving in water in the atmosphere
D) gases from air conditioners and refrigerators escaping into the atmosphere
gpt
The correct answer is 2: gases from burning coal and oil dissolving in water in the atmosphere.