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

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.

A．Human population expands at an exponential rate.
B．Population growth has shown fluctuation in demographic history.
C．Population growth can not be regarded as a social failure.
D．Increase in population is related to productivity.