The correct option is D 3, 1, 2
The sequence explains the theory of demographic transition.Before the economic modernizations, the country had stable or very slow growing population as a result of a combination of high birth rate and almost equally high death rate. With economic development, resulting in higher incomes, improved public health facilities, there was marked a decline in mortality that gradually raised life expectancy. With declining death rate but birth rate not falling correspondingly, the country passed through the second stage, marking the beginning of a demographic transition. Finally, the state third comes when the force and influence of modernization and economic development cause fertility to decline so that eventually falling birth rate converge with the lower death rate.