Ans.
Mycorrhiza is defined as a symbiotic relationship between the roots of vascular host plant and fungi. It shows a mutualistic association as both plant and fungi get benefit from this association.
The fungus provides nutrients to the plant as fungi have higher mineral absorption capacity from soil due to the presence of mycelia and hyphae. On the other hand, plants provide the fungus with direct access to food, in the form of sucrose, glucose, and other carbohydrates.
Thus, the correct answer is 'root.'