Why was Mexico concerned about Texas joining the United States?

Following archduke franz ferdinand's assassination, austro-hungarian leaders: a. aided the ottoman empire in its campaign to keep serbia under its control. b. executed nearly all prominent serbs living in austria-hungary c. threatened to invade serbia if serb leaders did not agree to a set of strict demands. d.. formed an alliance with great britain to protect austria-hungary from future attacks.

Was the civil war inevitable? could anything have been done through compromise to stop it, or did it have to happen?

Who were the “rough riders”? a. cuban revolutionaries who battled the spanish for independence b. a volunteer cavalry unit in the spanish-american war c. spanish generals in cuba who mistreated the civilian population d. newspaper owners who influenced public opinion by exaggerating the truth