Thanks for the question! Let’s take a look at this question. We’re told that there was a study in which customers who got change were given an extra dollar with their change. Only a few people gave the extra dollar back. The argument then concludes that of the people who received an extra dollar, most were dishonest.
We now need to come up with a question that helps evaluate the argument. Now notice something: it’s completely possible that people didn’t count their change, and so some of the people who didn’t return the dollar might be dishonest, they might just be a little clueless and not super observant. And so it would help to know if people counted their change or not, because if people did count their change and still didn’t give the money back, it’s much more likely they’re actually dishonest. Similarly, if they didn’t count their change, it’s more likely that they’re not dishonest.
(C), on the other hand, isn’t correct. It doesn’t matter what the people describe themselves as. Honest people might think they’re dishonest, and dishonest people might (dishonestly) describe themselves as honest. What matters is what the people actually do.
Hope this helps! Feel free to ask any other questions that you might have.