The correct option is D Symbiotic association between a fungus and roots of higher plants
Mycorrhiza represents symbiotic association between a fungus and roots of higher plants. Mycorrhizae are considered to be a mutualistic relationship because both organisms are benefited. The fungus receives the products of photosynthesis from the plant and is thus freed from the necessity of finding its own sources of energy. At the same time the fungus grows out into the soil and retrieves nutrients, especially phosphorus and nitrogen, and passes these back to the plant.