The Graph Below Shows Estimated World Population for the Period $10 ^ { 7 }$

The graph below shows estimated world population for the period 4000 BC = 2000 AD. Note that the logarithm of the world population and not actual population is plotted on the vertical axis. This means, for example, that when the graph reaches 7 on the vertical scale, world population is $10 ^ { 7 }$ and when the graph reaches 9 on the vertical scale, world population is $10 ^ { 9 }$ Use the graph to answer the question.
-How does world population in the year 2000 AD compare with world population in the year 4000 BC?

A) The 2000 AD population is roughly three billion larger than the 4000 BC population.
B) The 2000 AD population is roughly thirty times as large as the 4000 BC population.
C) The 2000 AD population is roughly 44% larger than the 4000 BC population.
D) The 2000 AD population is roughly one thousand times as large as the 4000 BC population.