Rhizobium is a symbiotic nitrogen fixing bacteria and used as a biofertilizer in which of the following

Correct option is C

Rhizobium forms a symbiotic association with leguminous plants, where it lives in root nodules. In this association, bacteria fix atmospheric nitrogen and supply it to the host plant. Gram, being a leguminous crop, uses Rhizobium as a biofertilizer.
Information booster: Rhizobium bacteria convert atmospheric nitrogen into ammonia, which plants can readily use. The symbiosis benefits both partners, as plants receive nitrogen and bacteria obtain food and shelter. Rhizobium is crop-specific and different strains are used for different legume crops. Use of Rhizobium biofertilizer reduces dependency on chemical nitrogen fertilizers.
Why other options are incorrect: (a) Maize is a non-leguminous crop and does not form symbiosis with Rhizobium. (b) Paddy mainly associates with free-living or associative nitrogen fixers, not Rhizobium. (d) Sugarcane benefits from associative nitrogen fixers like Azospirillum, not Rhizobium.