Final answer:
Secondary disinfection's main purpose is to maintain a residual to inhibit microbial growth and prevent biofilm formation in the distribution system, not to neutralize taste and odor compounds or kill resistant pathogens like Cryptosporidium.
The Correct Option is; A) maintain sufficient residual in the water distribution system to inhibit microbial growth.
Step-by-step explanation:
Secondary disinfection of drinking water is important for several reasons. One of the main purposes is to maintain sufficient residual in the water distribution system to inhibit microbial growth.
Another reason is to prevent the formation of biofilms on pipes in the water distribution system. However, secondary disinfection is not primarily designed to neutralize taste- and odor-producing organic compounds or to kill Cryptosporidium and other resistant pathogens.
For Cryptosporidium, methods like ultraviolet disinfection are often more effective as this pathogen is highly resistant to chemical disinfectants like chlorine.