Both Ectomycorrhizal Fungi and Rhizobia Are Able to Supply Plants

Both ectomycorrhizal fungi and rhizobia are able to supply plants with usable forms of nitrogen. From what sources do rhizobia and ectomycorrhizal fungi that are associated with plants obtain nitrogen?

A) They both absorb ammonia from soil, which they nitrify to NO₂^- .
B) They both absorb N₂ from the atmosphere.
C) Fungi obtain nitrogen by decomposition of organic material, and rhizobia absorb N₂ from the atmosphere.
D) They both obtain nitrogen by decomposition of organic material.
E) Fungi absorb N₂ from the atmosphere, and rhizobia obtain nitrogen by decomposition of organic material.