Food chain in which microorganisms breakdown the food formed by primary producers is
Detritus food chain
The detritus food chain usually operates in soil or benthic zones where the first trophic level is made up of organic matter. The second trophic level is made up of microbes that are decomposers. They obtain energy by degrading complex organic matter formed by primary producers into simpler inorganic compounds.
Final answer
(B) Detritus food chain