The main debate between the North and South in the years leading up to the Civil War was over A. the South’s demand for higher tariffs on manufactured goods.

B.
the spread of slavery into the West.

C.
where the transcontinental railroad should be built.

D.
the North’s insistence that slavery must end in the South.

B.  the spread of slavery into the West.

Explanation:

It was an established fact in the years leading up to the Civil War that the South was pro-slavery and the North was Anti-slavery and so both sides had arguments about the spread of slavery into the western territories as those territories gained statehood.

The South wanted slavery to spread into the territories so that they would have more states which would give slavery more representation in Congress and therefore keep the practice going. The North wanted the territories to be free for the same reason.

in february 1787, congress decided that a convention should be convened to revise the articles of confederation, the nation’s first constitution. in may, 55 delegates came to philadelphia, and the constitutional convention began. debates erupted over representation in congress, over slavery, and over the new executive branch. the debates continued through four hot and muggy months. but eventually the delegates reached compromises, and on september 17, they produced the u.s. constitution, replacing the articles with the governing document that has functioned effectively for more than 200 years.

your answer would be just capitalism.