What role do fungi serve in ecosystems?

Fungi play a crucial role in ecosystems primarily as decomposers, and this function is vital for nutrient cycling. They break down complex organic materials, such as dead plants and animals, as well as waste products, which releases essential nutrients back into the soil. This process not only aids in the recycling of nutrients but also supports the growth of plants and other organisms, thereby maintaining ecosystem health.

While they do exert some influence on biodiversity by contributing to a diverse community of organisms, the most significant ecological function of fungi is their decomposition ability. They establish vital symbiotic relationships with plants, such as mycorrhizal associations, which further enhances nutrient availability. In contrast, photosynthesis is the domain of plants and certain protists, and fungi do not fit this role. They are not primary producers but rather occupy a different niche in the food web, making option C the most accurate representation of their ecological role.