The correct answer is (a) 17.6 %.
India’s population grew from 1.028 billion in 2001 to 1.21 billion in 2011, an increase of 17.6%. This was the lowest rate of population growth in India since 1921. The decline in population growth is due to a number of factors, including a decline in fertility rates, an increase in urbanization, and an increase in the average age of the population.
Option (b) is incorrect because the population growth rate in India during the decade 2001-2011 was 17.6%, not 19.5%.
Option (c) is incorrect because the population growth rate in India during the decade 2001-2011 was 17.6%, not 21%.
Option (d) is incorrect because the population growth rate in India during the decade 2001-2011 was 17.6%, not 22%.