Many legume plants have specialized fungi, known as mycorrhizae, living in their roots providing inorganic nutrients such as phosphates and nitrates. The fungus gains valuable nutrients from the roots of the plants. This relationship is an example of:

Symbiotic relationship(mutualistic)

Explanation:

Mycorrhiza is a symbiotic relationship that is formed between specialized fungi and roots of legume plants. In this relationship both the interacting species get benefit from its partner so it is a mutualistic relationship.  

In mycorrhiza fungi help the leguminous plant to absorb nutrients and water and the leguminous plant provide a source of energy which is carbohydrate to the fungi.  

Therefore both the members get to benefit from the presence of each other. Therefore this relationship is an example of a mutualistic relationship.