Differentiate between primary disinfection and secondary disinfection in water treatment.

• A. Primary disinfection reduces pathogens in treatment; secondary disinfection maintains a residual in the distribution system to protect water quality.
• B. Primary disinfection maintains residual; secondary disinfection reduces pathogens.
• C. Primary uses only UV; secondary uses only chlorine.
• D. Primary is for taste; secondary is for color.

Answer: (A)