The correct options are
A Screening
B Sedimentation
C Flocculation
In Primary treatment, the solid waste which is not soluble in water is separated out using screening, sedimentation and flocculation. Screening, filters out the waste that are larger in size. Sedimentation uses gravity to remove solids that settle down. Fine particulates are clumped together in flocculation. Bioremediation is an example of Secondary treatment.