How many significant demographic changes ever occurred in the past one million years

A．describe the superiority of the developed nations
B．stress the need for scientific and educational development
C．prove that underdeveloped nations are backward
D．show the poverty and ignorance of Third World countries

A．The population is always in constant geometric growth.
B．Rapid growth is followed by stable growth.
C．Decelerated growth is following by a decline.
D．No growth at all.