Which concept describes early earth as separated into layers by gravity, with each deeper layer denser than the layer above?

a. centrifugal force
b. density stratification
c. seismic theory
d. tectonic theory
e. continental drift

Although china’s total economic output, measured by gross domestic product (gdp), is third largest in the world, it is considered a developing nation. what is most likely the most important factor for this designation? a. china’s government spends money on things that do not benefit human development. b. china has a large population, so its gdp per person is only modest. c. china has a strong economy but weak literacy and school attendance rates. d. china’s high rates of disease offset the country's economic gains.