Which of the following best explains why the term fifty-four forty was related to American expansion in the West? It named the coordinates of the Republic of Texas.
It named the coordinates of the Oregon Territory.
It referred to the number of square miles Mexico ceded to the US.
It referred to the year that James Polk won the presidency.

The correct answer is - It named the coordinates of the Oregon Territory.

Explanation:

The term Fifty - four - forty is a very famous term during the 1850s, it was the latitude line of 54 degrees, 40 minutes of the northern boundary of Oregon. In the early 1840s, no one knew exactly about the location of Oregon country.

"Fifty-four forty or fight!" is the term or slogan that means that the United States would accept nothing less than all of the Oregon Country that they believed at latitude line of 54 degrees, 40 minutes, as far north as the border of Alaska. This slogan was the campaign slogan of Polk that helped to victory against all odds.