There is a pair of doors that were locked at D/1-2/2 and D/1-2/4, both of these doors are relevant to this Quest. To solve this quest (and not open the wrong door) you'll have to have read the "Elemental" books in each of the secret portions of the 4 mazes. Though if you want a hint to which element each set of doors is asking about, go between the two doors and check, there will be a hint for each set. The answers are below: