The main issue that led to the Great Compromise was the issue of representation. The small states in the country thought that every state should have equal representation in the Congress. They thought the states ought to be equal to one another.
It’s D, providing for a stable currency
It allowed for slaves to be counted as people halfway to please the abolitionists, but didn't allow them to be citizens to please the pro-slavery side.
Most of the railroads were individually owned so to support an internal east west trading system all the companies would have to cooperate