A serviceable landing light is required equipment on aircraft
Why this is the answer
Per CAR 605.16, a serviceable landing light is required when carrying passengers at night. The weight/aerodrome-lighting qualifiers in the other options are distractors — the trigger is simply carrying passengers at night.
Reference
CARs 605.16 – Power-driven Aircraft – Night VFR
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.