Which of the following is known as "effluent polishing"?

A. it is to settle out biological flock through a secondary classifier

B. it is to provide final treatment stage to raise effluent quality before discharged where disinfection is practiced

C. it is the final treatment stage of treatment to raise effluent quality where disinfection is not practiced

D. it is the effluent treatment done with ultraviolet

Answer: Option B