Which malaria reduction strategy would be most harmful to humans? 

A)  spraying heavier doses of DDT on swamps and estuaries 
B)  using mosquito nets dipped in permethrin 
C)  increasing water flow in irrigation systems 
D)  cultivating fish that feed on mosquito larvae

Spraying heavier doses of DDT can have harmful effects on human health and the environment. DDT is a persistent organic pollutant that can accumulate in the food chain and has been linked to cancer, birth defects, and other health problems. While it is effective at killing mosquitoes, it can also harm other insects, birds, and mammals. Mosquito nets dipped in permethrin, increasing water flow in irrigation systems, and cultivating fish that feed on mosquito larvae are all safer and more sustainable malaria reduction strategies.