According to the Census of India, 2011 the percentage growth of population in country during the period of 2001-2011 was:

The correct answer is B) 17.70. Census 2011 recorded the population at 1,210.85 million, against 1,028.74 million in Census 2001. That is a rise of about 182.1 million, or 17.70%, the decadal growth rate reported in the Census 2011 final population totals.

• A) 31.34 is far too high. Growth had already fallen well below this level by 2001-11.
• C) 13.31 is too low. It does not match the census figure for this decade.
• D) 23.85 is the trap. It is almost the 1981-91 decadal growth (23.86%), a decade the question does not ask about.

The core concept is decadal growth rate, computed as the percentage change in population between two census years. For Mains (GS-1 Population and GS-2 welfare schemes), note the steady decline from the 1971-81 peak of about 24.7% to 17.7% in 2001-11. This decline underpins the debate on the demographic dividend and the success of family planning and female education.

Trap: Candidates pick D because it sits close to a remembered earlier decade figure. Always check the exact census years in the question.