How exactly are Regents students selected?

I tried searching around but I couldn’t find anything. Does anybody know what criteria the UC’s use to select its regents candidates? Is it simply based off stats and ECs, just essays, or is it more holistic? I read somewhere that some UC’s use a 1-5 rating system for its applicants, is the regents candidacy awarded to those who luckily score multiple 1’s?

I asked admissions reps from multiple UCs who came to my school about this and none of them were able to give me a straight answer. What they told me is that they award regents to the top x% of applicants and that the award is “holistic”…there is no formula for determining who receives the scholarship. However, if you look at the threads for who received regents, it seems to me that scores and especially grades are weighted more heavily than essays or EC’s.