An insect is food for a salmon. Water carries a rock downstream. A tree removes a gas from the air. A flower makes food for a butterfly.
Which example shows a relationship between a living thing and a nonliving thing?

Options:
- An insect is food for a salmon.
- Water carries a rock downstream.
- A tree removes a gas from the air.
- A flower makes food for a butterfly.

A tree removes a gas from the air.