I got all of them right. Several Years ago, I purchased an L1a1. Since it was in used condition, I wanted to have it modified because of the crappy things done to it to make it legal (barrel was cut to take the old flash suppressor off at the threads and the pistol grip was replaced by a monstrocity of a thumbhole stock that just plain sucked).
I also didn't want the BATF breaking down my door because of some "questionable" mods. So, I had to find out exactly what was acceptable for modifications. Some laws are just plain silly made by the ignorant.