Shady areas increased. Food sources increased. Oxygen levels increased. Available water increased.
I gave my students this multiple choice question: One year, the oak trees in a park began producing more acorns than usual. The next year, the population of chipmunks in the park also increased. Which best explains why there were more chipmunks the next year?

Only one answer is correct among these 4 choices:
- Shady areas increased.
- Food sources increased.
- Oxygen levels increased.
- Available water increased.

Could you tell me which one is correct?

Food sources increased.