The Answer To Your Question is B. Alignment.
Hope It Helps
For when they took over land? well you have to know that Mexico did not want to give land to America. Eventually though, due to Mexico not having alot of people to live on said land they told Americans that they could settle there .. ONLY if they became Mexicans and they converted to Catholicism. Americans of coarse agreed...BUT......many didn't fuffil that promise . It could be said and arued that the domanent strategy for America was to settle on the land and take it over from the inside.
The first president was C. George Washington.
I believe the answer you are looking for is the homestead act of 1862
