Question ID:PT86 S1 Q19 Passage:Researcher: In an experiment, 500 families were given a medical self-help book, and 500 similar families were not. Over the next year, the average number of visits to doctors dropped by 20 percent for the families who had been given the book but remained unchanged for the other families. Since improved family health leads to fewer visits to doctors, the experiment indicates that having a medical self-help book in the home improves family health. Stem:The reasoning in the researcher's argument is questionable in that Correct Answer Choice:DChoice A:it is possible that the families in the experiment who were not given a medical self-help book acquired medical self-help books on their own Choice B:the families in the experiment could have gained access to medical self-help information outside of books Choice C:a state of affairs could causally contribute to two or more different effects Choice D:two different states of affairs could each causally contribute to the same effect even though neither causally contributes to the other Choice E:certain states of affairs that lead families to visit the doctor less frequently could also make them more likely to have a medical self-help book in the home