The Indigenous peoples of Washington were forced to accept the U.S. government's idea of landownership because:
D. their land was invaded by white American settlers.
This answer is correct because historically, white American settlers moved into Indigenous lands, leading to conflicts and ultimately the displacement of Indigenous peoples from their territories. The settlers claimed the land as their own, disregarding the Indigenous peoples' ownership and rights. This forced the Indigenous populations to accept the U.S. government's concept of landownership that favored the settlers, leading to loss of traditional territories and resources.
