An association of private schools has published a study which lays down that no study of school quality is to be trusted unless it is made by a body with no interest in the answer, and which concludes that the district's private schools teach better than its government schools. Which of the following, if true, most weakens the association's conclusion?

The study announces a test for trustworthy studies and then fails it: the body that made it exists to raise the standing of one of the two kinds of school it was weighing. The conclusion is therefore untrustworthy by the association's own rule, and no separate charge of dishonesty is needed to reach that result. The relative numbers of pupils describe the district's schooling without bearing on who made the study or how. The length of the bulletin is a fact about the printing. And that some private schools are dear bears on who can reach them, which is an objection to private schooling as a policy and not to the study's finding about teaching.