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 :)
Many of the agricultural workers in central Asia's cotton fields are children. The correct option among all the options that are given in the question is the second option or option "b". These fields favored child labor which is crime in the modern world. I hope the answer comes to your help.
B. I think if it’s wrong I really sorry. Have a nice day.