单选题 In malaria-infested areas, many children tend to suffer several bouts of malaria before becoming immune to the disease. Clearly, what must be happening is that those children's immune systems are only weakly stimulated by any single exposure to the malaria parasite and need to be challenged several times to produce an effective immune response.
Which of the following, if true, most seriously undermines the explanatory hypothesis?

A、 Immediately after a child has suffered a bout of malaria, the child's caregivers tend to go to great lengths in taking precautions to prevent another infection, but this level of attention is not sustained.
B、 Malaria is spread from person to person by mosquitoes, and mosquitoes have become increasingly resistant to the pesticides used to control them.
C、 A certain gene, if inherited by children from only one ot their parents, can render those children largely immune to infection with malaria.
D、 Antimalaria vaccines, of which several are in development, are all designed to work by stimulating the body's immune system.
E、 (E) There are several distinct strains of malaria, and the body's immune response to any one of them does not protect it against the others.

【正确答案】 E

【答案解析】[解析] 本题比较简单，我们重点是去反对段落里的解释性假说，即孩子们通过暴露于疟原虫下并与之抗争数次可产生有效免疫反应。如果疟疾种类不止一种，而人们对其中一种的免疫反应并羽能保护人体抵抗其他几种，正如(E)所说，那么孩子对疟疾产生免疫力可能还要借助于其他途径，所以(E)Weaken了解释性假说，所以(E)正确；(C)易误选，但(C)讨论的仅仅是特定的一组孩子，而未说明一般的孩子，因此错误。