What is demographic divide? In which year is this divide seen in India and why?

When there is a sudden fluctuation in population or the growth rate declines, it is called demographic divide.
(i) In India, it took place in 198 I as the rate of growth started declining gradually.
(ii) It happened as the birth rate declined rapidly during this period.
(iii) Since 1981, birth rates declined, resulting in a gradual decline in the rate of population growth.