This is the most logical answer out of the options presented in this question. It is unlikely that the Civil War affected American Indians in this way. American Indians fought in the Civil War, with some tribes joining the Union and others joining the Confederacy. Some tribes had people fighting on both sides of the war. This led to division among Native people, not union.
Assuming that this is referring to the same list of options that was posted before with this question, consumer goods and the means to buy them most led to more advertising.
