Answer:
a. they helped its economy grow rapily
I think you probably wanted to post this as a response to something and not it's own post but maybe you did want it as it's own post and like that's fine too, just thought I'd point it out
Answer: The opposing powers in a proxy war use others to fight on their behalf.
Stalin urged them to help the Soviets
As a result, by 1859, tensions between North and South were heightened with agitation coalescing around the slavery issue on both sides.