One of the compromises made between northern and southern states during the constitutional convention of 1787 concerned
a.)western land claims
b.)counting slaves in the population
c.)allowing new states into the union
d.)regulation of interstate commerce

One of the major compromises made between the Northern and Southern states during the Constitutional Convention of 1787 concerned B) counting slaves in the population. As a result of this compromise the states agreed to count each slave as 3/5 of a person and the compromise thus became known as the three fifths compromise. 

Actually, it the correct answer is A, C, and D. The Northwest Ordinance of 1787 allocated parts of the Ohio Valley for soon-to-be states. It prohibited the introduction of slavery to the new region. Also, this was under the Articles of Confederation, where there was no regulation on Interstate Commerce (which was fixed in the Constitution of 1789). Under the Articles, each state had its own currency, which cause much frustratin.

For example: In Vermont, a bottle of molasses might have cost 2 shillings, but in Georgia an identical bottle might have cost 92 cents.