What process is aided by lightning legumes and soul bacteria

"Key players in this process are legumes and the symbiotic bacteria which are associated with the legume's root nodules. Thesebacteria are known as nitrogen-fixingbacteria. These organisms convert nitrogen in the soil to ammonia, which can then be taken up by plants."

source :https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.cas.miamioh.edu/mbi-ws/biogeochemicalcycles/Nitrogen/nitrogen.htm&ved=2ahUKEwij4MbP7&usg=AOvVaw1NLaMkgl0OB4rDyi07baWD&cshid=1550478305317

hey your not cool]      

bcde is the incorrect answer it is a