Explanation:

• The History of Census began with 1800 when England had begun its Census but the population of dependencies was not known at that time. In its continuation, based on this methodology census was conducted in town of Allahabad in 1824 and in the city of Banaras in the year 1827-28 by James Prinsep. The first complete census of an Indian city was conducted in 1830 by Henry Walter in Dacca.
• A systematic and modern population census, in its present form was conducted non synchronously between 1865 and 1872 in different parts of the country. This effort culminating in 1872 has been popularly labeled as the first population census of India.
• The year 1921 is often referred to as the “Year of the Great Divide,” the last period in which India’s population declined, due to the effects of famine.

Hence only statement 2nd is correct.