I think it stands for Australian Defence Identification Zone, but anywho its basically airspace around an Airforce Aerodrome. The question relates to say restricted space around an Airforce Aerodrome and an aerodrome which is located inside that restricted airspace.
Neither B nor D is technically correct. Whilst B states 5nm the AIP states its actually 10nm so technically that answer is incorrect. D is also technically correct due to AIP 1.12-1, 1.1.4 (a) a flight originating within a ADIZ which maintains a steady outbound track; So D is also correct EXCEPT it doesn't specifically state whether your moving with a steady outbound track or whether the flight just originates from there.
Air Law is all about interpretation as i'm sure you've already learnt, by far one of the most annoying exams especially with an 80% pass mark required.