Fungal association of roots of higher plants in mycorrhiza is

The correct option is B Mutualism
In mutualism or symbiosis both the organisms in the association are mutually benefitted and further this association is obligatory, i.e., necessary for the existence of both organisms. Mycorrhiza is an example of symbiosis. It is an association between roots of higher plants and fungal hyphae. The fungal hyphae supply water and nutrients to the plant and in turn get food from the plant. So, both the organisms are mutually benefitted.