66. What would be the most effective method of reducing the incidence of blood flukes in a human population?
(A) Reduce the mosquito population.
(B) Reduce the freshwater snail population.
(C)Purify all drinking water.
(D) Avoid contact with rodent droppings.
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統計: A(8), B(33), C(13), D(4), E(0) #2911822
統計: A(8), B(33), C(13), D(4), E(0) #2911822