Which of the following statements about the building of Canada's transcontinental railway is TRUE?

A. The workers faced the same challenges in each section of the country.
B. The completion of the railway brought many newcomers to the West and changed the prairies forever.
C. Building the railway was expensive; the cost of one kilometre of track averaged a million dollars.
D. The workers did not build the railway during the months of extreme heat and extreme cold.
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I am confused, can someone help me? A link would be helpful, too, as I need some more context. Thank you!

Well, down south in the US, the railways kind of opened up development of much of the country west of the Mississippi. I kind of suspect the same sort of action up north.