Question: Information:  - Air Canada is the flag carrier and largest airline of Canada. The airline, founded in 1937, provides scheduled and charter air transport for passengers and cargo to 182 destinations worldwide. It is the world's tenth-largest passenger airline by fleet size, and is a founding member of the Star Alliance. Air Canada's corporate headquarters are located in Montreal, Quebec, while its largest hub is at Toronto Pearson International Airport. Air Canada had passenger revenues of CA$13.8 billion in 2015. The airline's regional service is Air Canada Express.  - Air BC was an airline headquartered in Richmond, British Columbia, Canada. It is now part of Air Canada Jazz. This regional airline primarily flew turboprop aircraft but also operated jets as well as an Air Canada Connector carrier on behalf of Air Canada via a code share feeder agreement.  - Air Nova was an airline based in Enfield , Nova Scotia , Canada that became part of Air Canada Regional in 2001 . In 2002 the merger of Air BC , Air Ontario , Air Nova and Canadian Regional Airlines was finalised with the launch of a new name and brand - Air Canada Jazz .  - Canadian Regional Airlines was an airline headquartered in Calgary International Airport in Calgary, Alberta, Canada. It is now part of Air Canada Jazz.  - Canada (French: ) is a country in the northern half of North America. Its ten provinces and three territories extend from the Atlantic to the Pacific and northward into the Arctic Ocean, covering , making it the world's second-largest country by total area and the fourth-largest country by land area. Canada's border with the United States is the world's longest land border. The majority of the country has a cold or severely cold winter climate, but southerly areas are warm in summer. Canada is sparsely populated, the majority of its land territory being dominated by forest and tundra and the Rocky Mountains. About four-fifths of the country's population of 36 million people is urbanized and live near the southern border. Its capital is Ottawa, its largest city is Toronto; other major urban areas include Montreal, Vancouver, Calgary, Edmonton, Quebec City, Winnipeg and Hamilton.  - Nova Scotia (Latin for "New Scotland"; French: "Nouvelle-Écosse") is one of Canada's three Maritime provinces, and one of the four provinces which form Atlantic Canada. Its provincial capital is Halifax. Nova Scotia is Canada's second-smallest province, with an area of , including Cape Breton and another 3,800 coastal islands. As of 2011, the population was 921,727, making Nova Scotia the second most-densely populated province in Canada with almost .  - Vancouver, officially the City of Vancouver, is a coastal seaport city on the mainland of British Columbia, Canada, and the most populous city in the province.  - YYC Calgary International Airport, originally named McCall Field , is the international airport that serves Calgary, Alberta, Canada and the surrounding region; it is situated approximately northeast of downtown Calgary. The airport offers scheduled non-stop flights to major cities in Canada, the United States, Mexico, the Caribbean, Central America, Europe and East Asia.    What object entity has the relation of 'airline hub' with the subject 'air nova'?   Choices: - calgary international airport  - halifax  - toronto pearson international airport  - vancouver
Answer:
halifax