One reason why people should be aware of the impact of their actions on the environment is that

there are so many examples for that in different areas, like biology experiment carried out in our lab recently.

here's one link:

some fungi obtain their nutrients from a living host (plant or animal) and are called most biotrophic fungi have fairly narrow host ranges—they are specialized on a limited called rhizomorphs that allow the fungus to grow from one tree to another. ascospores are formed inside a sac-like structure called an ascus. so your answer is a