The mouse went to sleep. The mouse ate some food. The mouse started running. The mouse detected an odor.
I gave my students this multiple choice question: A mouse's rate of carbon dioxide output increased. Which of the following most likely happened?

Only one answer is correct among these 4 choices:
- The mouse went to sleep.
- The mouse ate some food.
- The mouse started running.
- The mouse detected an odor.

Could you tell me which one is correct?

The mouse started running.