Where taxiway holding positions have not been established, aircraft waiting to enter an active runway should normally hold
Why this is the answer
Where no taxiway holding position is marked, aircraft should hold 200 ft back from the runway edge (TC AIM-RAC, Taxi Holding Positions) to stay clear of aircraft using the runway.
Reference
TC AIM-RAC – Taxi Holding Positions
Question reproduced verbatim from Transport Canada’s PSTAR Study and Reference Guide (TP 11919E). The answer key is Transport Canada’s; the explanation is ours.
A study aid — not a substitute for the official guide, the CARs, or your instructor.