Boundary line between Canada and United States is_________?

A. 17th Parallel Line
B. 38th Parallel Line
C. 47th Parallel Line
D. 49th Parallel Line 

The treaty established the 49th parallel from the Rocky Mountains to the Strait of Georgia as the boundary between the United States and British Canada. … In 1818, a U.S.-British agreement had established the border along the 49th parallel from Lake of the Woods in the east to the Rocky Mountains in the west.