The correct option is A 1961 - 1971
The percentage of urbanisation increased from 18% in 1961 to 31.2% in 2011. The lowest growth in urbanisation was 0.2%, seen between 1961 and 1971. The growth in urbanisation was highest- around 5% - between 1971 and 1981. Post-1971, the rate of urbanisation in the country has seen a steady increase, all the way till 2011. The trend of increasing urbanisation is continuing.