English Language · English

Which choice completes the text with the most logical and precise word or phrase? In habitats with limited nutrients, certain fungus species grow on the roots of trees, engaging in mutually beneficial relationships known as ectomycorrhizae: in this symbiotic exchange, the tree provides the fungus with carbon, a nutrient necessary for both species, and the fungus ______ by enhancing the tree's ability to absorb nitrogen, another key nutrient, from the soil.