Why are sedimentation ponds useful for reducing the affects of soil erosion?

Which best expresses the radical republican philosophy of reconstruction? a. the confederate states were conquered territories that should be ruled by military governors. b. the southern states actually never left the union. c. if ten percent of the voters of a state that had seceded took an oath of allegiance to the union, then it should be readmitted as a state.

Give an example of a situation in which an individual's pursuit of economic self-interest may not benefit but instead harm the rest of society

Restricting immigrants from entering a country may be based on what belief?