Chemical coagulation, flocculation, sedimentation, and filtration primarily remove which of the following?

Chemical coagulation, flocculation, sedimentation, and filtration are critical processes in water treatment, particularly in the removal of various pathogens and particles from water.

Coagulation involves using chemicals to destabilize fine particles, which causes them to clump together into larger aggregates known as flocs through the flocculation process. These larger particles can then settle out of the water during sedimentation. Finally, filtration captures remaining particles and microorganisms, including bacteria, viruses, protozoa, and helminths, as the water passes through filter media.

Given these processes are effective against a wide range of potential contaminants, the correct answer encompasses all categories listed. The effectiveness of these methods in removing most bacteria, viruses, protozoa, and helminths highlights their comprehensive nature in ensuring safe water supply. This makes option D the best choice, as it includes the removal of all mentioned pathogen groups through the combined effects of the treatment steps.