GMAT Critical Reasoning
Some batches of polio vaccine used around 1960 were contaminated with SV40, a virus that in monkeys causes various cancers. Some researchers now claim that this contamination caused some cases of a certain cancer in humans, mesothelioma. This claim is not undercut by the fact that a very careful survey made in the 1960s of people who had received the contaminated vaccine found no elevated incidence of any cancer, since___________.
- A most cases of mesothelioma are caused by exposure to asbestos
- B in some countries, there was no contamination of the vaccine
- C SV40 is widely used in laboratories to produce cancers in animals
- D mesotheliomas take several decades to develop
- E mesothelioma was somewhat less common in 1960 than it is now
Correct Answer: D