Explanation:

The growth rate of population in India over the last one century has been caused by annual birth rate and death rate and rate of migration and thereby shows different trends. There are four distinct phases of growth identified within this period:

• Phase I: The period from 1901-1921 is referred to as a period of stagnant or stationary phase of growth of India‘s population, since in this period growth rate was very low, even recording a negative growth rate during 1911-1921. Poor health and medical services, inefficient distribution system of food and other basic necessities were largely responsible for a high birth and death rates in this period.
• Phase II: The decades 1921-1951 are referred to as the period of steady population growth. An overall improvement in health and sanitation throughout the country brought down the mortality rate.
• Phase III: The decades 1951-1981 are referred to as the period of population explosion in India, which was caused by a rapid fall in the mortality rate but a high fertility rate of population in the country. International migration bringing in Tibetans, Bangladeshis, Nepalis and people from Paksitan contributed to high growth rate.
• Phase IV: In the post 1981 till present, the growth rate of country‘s population though remained high, has started slowing down gradually. o Hence only pair 1 is correctly matched.