The term population explosion means

The world population in $1900$ was ........ billion,which increased rapidly to ........ billion in $2000$ and reached ........ billion in $2011$.

Which of the following does not help in the control of population growth?

Which of the following can be taken as characteristic demographic features of the developing countries?
$(a)$ High fertility rate
$(b)$ Rapidly rising mortality rate
$(c)$ Very young age distribution
$(d)$ Rapid population growth
$(e)$ Rapidly falling mortality rate
$(f)$ Very old age distribution

The total population of the world by the end of the $20^{th}$ century reached approximately:

Choose the correct causes for the population growth.
$I$. Decline in death rate
$II$. Rapid increase in $MMR$ and $IMR$
$III$. Rapid decline in $MMR$ and $IMR$
$IV$. Increase in the number of people in the reproductive age group
$V$. Rapid increase in the death rate