Triple

Target entity: United States westward expansion
Context triple: [Yakima War, hasCause, United States westward expansion]

• A. United States territorial expansion chosen
  United States territorial expansion refers to the historical process by which the United States grew from a cluster of Atlantic coast colonies into a transcontinental nation through purchases, wars, treaties, and settlement.
• B. California annexation by the United States
  California annexation by the United States was the mid-19th-century process, culminating in the Mexican–American War and the 1848 Treaty of Guadalupe Hidalgo, by which the U.S. took control of Mexican Alta California and incorporated it into its territory.
• C. Northern Expansion Doctrine
  The Northern Expansion Doctrine was an Imperial Japanese military and political strategy that advocated expansion into Siberia and the Soviet Far East to secure resources and strategic dominance.
• D. Oregon territorial period
  The Oregon territorial period was the era from 1848 to 1859 when the region that would become the state of Oregon was governed as a U.S. territory with its own appointed and elected officials.
• E. Southern Expansion Doctrine
  The Southern Expansion Doctrine was an early 20th-century Japanese imperialist strategy advocating political, economic, and military expansion into Southeast Asia and the Pacific.
• F. None of above.
• G. Unsure - the case is ambiguous/there is not enough information to decide.