There are four states in the U.S. that begin with "I": lowa, Illinois, Idaho, and Indiana
B & C in my opinion. If it asks for one— B. is what I would choose.
The math suggests that for every parsec the rate of moving away is 71 km/s, so when two galaxies are separated by two parsecs we come to 142 km/s speed of moving away from each other. If we take the first light ever (from what is known so far) the cosmic microwave radiation, is 46 billion light-years away from us at all directions, which comes at 4,200 megaparsecs, which comes at 13.7 billion light-years, so it will come to 29,820,000 km/s. It all depends from the distance between the galaxies which is calculated by their type of colour and movement in comparison to other galaxies.
A biggie: the transcontinental railroad. Because it would economically improve wherever it was, both the North and the South competed for the railroad to be in their respective territory, evidenced by the Kansas-Nebraska Act and the Gadsen Purchase and induction of California as a free state in 1860.
In addition: people could get land cheap because it was abundant and might leave to start afresh economically.
There's other stuff I can't remember as clearly, but there's a little and I hope it helps :)