A Control Zone normally is controlled airspace extending upwards from
Why this is the answer
Per CAR 101.01 and TC AIM-RAC, a control zone is controlled airspace that extends upward from the surface of the earth (typically to 3,000 ft AAE) to keep IFR and VFR traffic apart around a busier aerodrome. The 2,200-ft and 700-ft bases describe other airspace structures.
Reference
CARs Part 101.01 – Control Zone TC AIM-RAC – Control Zones
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.