Answer: I believe it is D, the Nervous System.
Explanation:
Topsoil is the most fertile soil layer for plants.
<span>Lithosphere, I know this because I got it right on usatestprep</span>
Answer:
Lichens are not parasitic when they grow on trees, they just use the tree bark as a home. They enrich the soil by trapping water, dust and silt. When lichens die they contribute organic matter to the soil, improving the soil so that other plants can grow there.
Found in eukaryotic cells