GMAT Critical Reasoning (CR) | Re: More citizens of Alphaville tune in to nightly news programs

Whenever an explanation is made of a finding/phenomenon - the assumption is that there are no other explanations that could explain the finding/phenomenon.
Answer choice A presents a data that shows why more people are viewing the news item in city A than city B. In doing so, this makes the explanation (=conclusion) less likely to be true.
Another way to look at this argument is representative sampling : ...

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