We are asked to determine which of the given options is a source of biomass.
Recall that biomass is plant or animal based waste that can be used for energy generation.
Clean coal is a fossil fuel, not biomass.
Uranium is the source of nuclear energy and Radioactive waste is the hazardous waste released as a result. Hence, it is not a biomass source either.
Sewage sludge is the source of biomass.
Therefore, sewage sludge is the correct answer.
