In the mid 1800 the specific network of routes an safe houses used by people exscaping slavery known as

The Underground Railroad was a network of secret routes and safe houses established in the United States during the early to mid-19th century, and used by enslaved African-Americans to escape into free states and Canada. The scheme was assisted by abolitionists and others sympathetic to the cause of the escapees.

option a

explanation:

to cleberate the end of their war

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.