The sex ratio (number of females per 1000 males) in India has shown fluctuations over the census decades. Looking at the data: - 1931: 950, 1941: 945 (Decline of 5) - 1961: 941, 1971: 930 (Decline of 11) - 1981: 934, 1991: 927 (Decline of 7) - 2001: 933, 2011: 943 (Increase of 10) Comparing the declines in the given options, the sharpest decline in the sex ratio occurred between 1961 and 1971, with a drop of 11 points. This was the lowest sex ratio recorded since 1901 at that time.