1. what was the cause of the mexican-american war? a. a dispute over the border between the two countries b. control over the southern portion of new mexico c. the declaration of independence by texas d. the status of mexican citizens living in texas 2. why did president james k. polk support the u. s. acquisition of both texas and the entire oregon territory? a. he needed to win the support of southern slaveholders. b. he believed in manifest destiny. c. he wanted to drive great britain out of north america. d. he wanted to provoke a war with mexico. 3. what did texas become when it declared its independence from mexico? a. the state of texas b. the alamo c. the texas territory d. the lone star republic