Which year is known as 'year of great divide' for India's population?

1921 is known as the 'year of great divide' in India's demographic history because it marked the point where India's population growth rate changed from negative/very low to consistently positive. Before 1921, population growth was stagnant or declining due to famines, epidemics, and colonial policies. After 1921, population began growing steadily. Options B, C, and D are not recognized as the year of great divide.