Answer:
Correct answer is The rise of big businesses, creation of monopolies and the gaining of massive sums of wealth.
Step-by-step explanation:
This is the correct answer as it refers to period of second part of 19th Century when United States become an industrial power.
First option is not correct as expansion is a process of imperialism.
Second option is not correct as it refers to revolutionary period in Europe during 18th and 19th Century.
Last option is also not correct as it refers to unrest started because of segregation and similar problems in the society.