Someone pls help me

The event shown in the map is a cause of which of the following? *pic*gadsden purchase battle of the alamo bear flag revolt settlement of texas

Which situation would be more likely to occur in the modern era than in earlier periods of human history

Historians use periodization in order to: a. decide when a certain historical even took place. b. divide history into units with distinct start and end dates. c. criticize arguments made about the past. d. organize history into different timelines