165 in June 2021, went from 91st to 89th percentile.

Ok, that makes sense. Thank you for clarifying this!

#help

Could someone help me explain what does the phrase "that which"(in the last sentence of the argument) refer to? I was confused by the phrase during the timed test. Upon review, I wonder if it refers to the 'explained function' in the previous sentence?

Thanks a lot!