They are broken down by ultraviolet light from the Sun. They are converted into nitrogen and oxygen. They rise through the atmosphere and go into outer space. They remain in the atmosphere for long periods of time.
I gave my students this multiple choice question: Large amounts of industrial gases are released into the atmosphere every day. What happens to those gases?

Only one answer is correct among these 4 choices:
- They are broken down by ultraviolet light from the Sun.
- They are converted into nitrogen and oxygen.
- They rise through the atmosphere and go into outer space.
- They remain in the atmosphere for long periods of time.

Could you tell me which one is correct?

They remain in the atmosphere for long periods of time.