单选题 We can infer from Paragraph 3 that ______.

A、 healthy people should live separately from unhealthy members of the family
B、 a germ-free home is not only possible, but significant
C、 unless you live with the vulnerable, it is pointless to sterilize the air
D, our immune systems are too weak to fight against the food poisoning bacteria

【正确答案】 C

【答案解析】[解析] 从第三段内容可知，C项为正确答案。