Really don’t want to get into this, but as a point of clarification, my comment about what admissions directors have said to me about their view on APs was in response to the original poster’s question about how much the number of APs taken matters. So, I am not saying anything about what/which APs. I repeated what Directors of Admissions from highly selective colleges and universities have said directly to me: they evaluate the APs taken relative to what is available to the student and what is typical in the school (so, for example, students who go to HS where there are no APs are not penalized); and that they do not want students feeling that they have to take more APs just to impress them.
As for this:
To the OP and other readers: this is a HS student given an explanation of another students experience. There is simply no way that the single factor factor of a low AP grade and a high classroom grade resulted in a student getting turned down by BU admissions. And that is not a guess or a hypothesis: I know current BU students who had low AP scores and high classroom grades (and at a great many other colleges, including HYP). It is not uncommon, for many reasons, including a poor alignment between the class as taught and the exam.