During the mexican-american war, the united states and mexico fought over land in the northwest. land in the southwest. independence for mexico. payment for california.

Correct  Land in the Southwest

Context/detail:

The Mexican Cession was territory ceded (meaning given up) to the United States in 1848 after the Mexican-American War.  The territory included lands that represent the full states of California, Nevada, and Utah, as well as large portions of  Arizona and New Mexico, and about a quarter of what would become the state of Colorado.  There was also a small section of Wyoming involved.  So that represents the bulk of territory that is in Southwest of the present United States.

while it was true that the cotton gin reduced the labor of removing seeds, it did not reduce the need for slaves to grow and pick the cotton.

explanation:

before eli whitney's invention of the cotton gin, picking and cleaning cotton was a slow, labor-intensive job. workers, usually slaves, had to pick the seeds from the cotton fibers by hand. this invention made it possible to grow large amounts of cotton on big farms and make money.

in 1862, president lincoln's emancipation proclamation opened the door for african americans to enlist in the union army. although many had wanted to join the war effort earlier, they were prohibited from enlisting by a federal law dating back to 1792.

explanation: