Which of the following is not correctly matched?

The correct answer is option 2: 1921-1951: Period of Rapid growth of population.

Option 1: 1911-1921: Negative Growth Rate of Population in India. This statement is correct because during this period India experienced a negative growth rate due to high mortality caused by epidemics, famines and other health crises.

Option 2: 1921-1951: Period of Rapid growth of population. This statement is not correctly matched because 1921–1951 is known as the period of steady population growth, not rapid growth.

Option 3: 1951-1981: Period of Population Explosion. This statement is correct because after 1951, death rates declined sharply while birth rates remained high, leading to rapid population increase.