If you were writing a thesis paper about events that legitimized the united states as an international power, which of the following would be most effective to include?

a. us purchase of alaska from russia in 1867
b. us victory in the spanish-american war in 1898
c. discovery of gold in california in 1848
d. defeat of the sioux at wounded knee in 1890

c, they united with once

since most of current immigration into the u.s., both legal and illegal, is coming from latin america. it would be very difficult to imagine or rationalize a country my fellow citizens are trying desperately to flee into, would pose a threat to my prosperity or freedom. since the u.s. has a long history of intervention, but no record of permanent occupation, i would not feel oppression is the main objective.  

the largest free trade nation, along with the largest gdp in the world wanting to expand it's economic policy on us, and including us, could only be positive. the u.s. government has no interest in, or way of simply forcing american culture on us. and has no track record of it. other nations that adopted american social culture, or "americanization" did so voluntarily, mainly through the choice of allowing american businesses and u.s. citizens to come into their nations, as free operatives.