The practice of allowing residents of territories to decide whether their land should be slave or free was called Option (C) popular sovereignty.
popular sovereignty, even named squatter sovereignty, in U.S. history, a controversial political doctrine according to which the individuals of federal territories should determine for themselves whether their territories would penetrate the Union as free or slave states.
Popular sovereignty stands for the principle that the authority of a state and its government is formed and sustained by the consent of its individuals, through their elected representatives (rule by the individuals), who are the source of all political power.
Hence, The practice of permitting residents of territories to determine whether their land should be slave or free was named Option (C) popular sovereignty.
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