As said above, a current Handbook is worth it's weight in gold for sure!
Using the quoted code "And the given answer:"No 240.21(B)(3)(4)"
I guess the quoted Article (in a stretch) could be cited as there is no AWG for the NM given. The stretch is compliance with "ALL" ((1) thru (5) and (1) thru (9) line items within 240.21 (B) (3) and (4)
18 yrs of being an inspector, and 50 years in the trade, I have never come upon NM for a transformer secondary.
