I am going through the Hooktheory I book. The review question at the end of Section 4.2 says “Rank the basic chords I, ii, iii, IV, vi in order by their utility as a pre-cadence chord.”
I don’t see where this is explicitly explained in the book. I understand that IV and ii are common pre-cadence chords, and iii has the least utility because it is more restrictive. Can you better explain the ranking: IV, ii, I, vi, iii?