D
Below is a question with multiple-choice answers. Choose the correct option based on your reasoning.

### Question:
Noah visited a park that had many oak trees. Which best describes the role of an oak tree in its ecosystem?

### Choices:
A. Oak trees can live for a long time.
B. Oak trees have leaves that change colors.
C. Oak trees have strong branches and trunks.
D. Oak trees are a source of food and shelter for animals.

### Answer:
