Answer:
The Quebec-City-Windsor Corridor
Step-by-step explanation:
The population density of Canada is 4 people/km².
The most densely-populated urban areas are Vancouver and Montreal (4800/km²).
The most densely populated region of Canada (80/km²) is the Quebec-City-Windsor Corridor. It contains almost half the population of Canada.
There are two main reasons for this.
(a) Climate
The region is entirely below the 47th parallel, so the summers are warm, the winters are not harsh, and the area is suitable for agriculture.
(b) Location
The corridor is close to the border with the United States and carries the bulk of Canada's trade with them. It makes sense for people to live as close to the US border as possible.