Musicologist: Many critics complain of the disproportion between text and music in Handel’s da capo arias.
Conclusion
The criticism that there's too little text, given the amount of music, in Handel's da capo arias is wrong (refuted).
rephrase: Even given the amount of music in this piece, it's okay for there to be so little text.
Evidence
Yes, the text repeats a ton, but that repetition serves a vital function, allowing the audience to focus on the music itself, which can speak to audiences of any language.
Evaluate
On Main Conclusion questions, the conclusion is almost always found in one of two places: - the very first sentence - after some "but / yet / however" rebuttal
Knowing that tendency helps to locate the conclusion here. The argument starts with "many critics", which potentially foreshadows a rebuttal. And then the "Yet" is one of the typical pivots.
The other indicator is the colon: <--- see? Colons introduce support.
Kathleen's desk is a mess: she has pens and paperclips and coffee stains everywhere.
So even if we don't count the "I refute this criticism" as the conclusion, we would use the "repetition serves a vital function". Why should we believe that? Because, [all the stuff after the colon].
Goal
Find an answer that either sounds like "this criticism is wrong" or one that sounds like "the repetition serves a vital function".