An airport is
Why this is the answer
An airport is a certified aerodrome. Per CAR 101.01 and CAR 302.03, an airport is an aerodrome for which an airport certificate has been issued; paved runways or a control tower are not what makes it one.
Reference
TC AIM-AGA – Aerodromes and Airports / General CARs 101.01 – Airport CARs 302.03 – Issuance of Airport Certificate Flight Training Manual Chapter 5 – Airport Operations
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.