If the change is the Industrial Revolution:
transcontinental railroad: helped to transport goods and get across the country
US army: helped to protect the US and make sure no one is going to break the new amendments
Discovery of resources in western land: Allowed the US to be able to expand and people would be able to live, could also give the US more money
Tribune is an official in ancient Rome chosen by the plebeians to protect their interests
During the Pequot War, an allied Puritan and Mohegan force under English Captain John Mason attacks a Pequot village in Connecticut, burning or massacring some 500 Indian women, men, and children.
The correct answer is Ethel and Julius Rosenberg.
Here is why the other answers are incorrect.
Joseph McCarthy was a US Senator focused on exposing communists in American society. His actions help sparked the House Un-American Activities Committee, which lead to innocent citizens being blacklisted by Congress.
Sacco and Vanzetti were two Italian immigrants convicted of murder. However, the lack of evidence caused citizens to believe that these individuals were wrongly convicted/executed due to their political belief in the system of anarchy.
Elizabeth Gurley was a woman's right activists and also helped in the development of labor unions during the World War I era.