About the job of bookkeeping, all of the following information is clear except ______.

A．To keep money for top companies.
B．To keep books for top companies.
C．To deal with accounts for top companies.
D．To deal with personal affairs for top companies.

A．Human population expands at a straight upward trend.
B．Population growth has shown ups and downs in demographic history.
C．Population growth can not be regarded as a social failure.
D．Increase in population is related to productivity.