gwd-28 Q29

Lofgren’s disease has been observed frequently in commercially raised cattle but very rarely in chickens.  Both cattle and chickens raised for meat are often fed the type of feed that transmits the virus that causes the disease.  Animals infected with the virus take more than a year to develop symptoms of Lofgren’s disease, however, and chickens commercially raised for meat, unlike cattle, are generally brought to market during their first year of life.

Which of the following is most strongly supported by the information provided?

1. The virus that causes Lofgren’s disease cannot be transmitted to human beings by chickens.
2. There is no way to determine whether a chicken is infected with the Lofgren’s disease virus before the chicken shows symptoms of the disease.
3. A failure to observe Lofgren’s disease in commercial chicken populations is not good evidence that chickens are immune to the virus that causes this disease.
4. An animal that has been infected with the virus that causes Lofgren’s disease but that has not developed symptoms cannot transmit the disease to an uninfected animal of the same species.
5. The feed that chickens and cattle are fed is probably not the only source of the virus that causes Lofgren’s disease.

我选的是B。为什么是C？请教NN

个人认为B错在过于绝对化，there is no way to determine，但实际上还是有少量的chicken被发现有受感染的（暗示有其他方法可以观察）

C正确因为由原文能推测出没能observe并不代表chicken就对这种疾病免疫。