Final answer:
The provinces that united to form the Dominion of Canada in 1867 were Nova Scotia, New Brunswick, and the Province of Canada, which included Ontario and Quebec. The union was part of a strategy for national defense and building a transcontinental railroad, and it retained ties to the British Empire.
Step-by-step explanation:
The provinces that united to form the Dominion of Canada in 1867 were Nova Scotia, New Brunswick, and the Province of Canada, which included Ontario and Quebec. This union was a strategic move to facilitate national defense and the building of a transcontinental railroad; it allowed Canada to self-govern while still remaining under the British Empire with Queen Victoria as its head of state. Sir John A. Macdonald, the nation’s first Prime Minister, played a crucial role in expanding the Dominion by negotiating the purchase of the Northwest Territories and convincing other provinces like Manitoba, Prince Edward Island, and British Columbia to join. The completion of the Canadian Pacific Railroad in 1885 further united the eastern and western coastal regions of Canada, important for the nation's cohesion and development.
Answer: A. Ontario, Quebec, New Brunswick and Nova Scotia