Answer:
![\boxed {\boxed {\sf D. \ Trees}}](https://img.qammunity.org/2022/formulas/biology/college/sbxl8pit5783csz6q6k9u93ugdkk1ta9p3.png)
Step-by-step explanation:
A biotic factor is a living part of an ecosystem. Animals, plants, fungi, and bacteria are all examples.
Let's examine the list we are given. We have temperature, precipitation (rain), soil, and trees.
Temperature, precipitation, and soil are not living. These are all abiotic factors. They are still part of the ecosystem, but they are not alive. So, that leaves trees, which are plants, as the biotic factor in a deciduous forest biome.