A steady red light directed at an aircraft means in flight on the ground
Why this is the answer
Per the TC AIM tower light signals, a steady red light tells an aircraft in flight to give way and keep circling, and an aircraft on the ground to stop. It does not mean the airport is unsafe.
Reference
TC AIM-RAC – Visual Signals TC AIM-RAC – Visual signals
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.