The correct answer is (a). The Constituent Assembly took 2 years 11 months 18 days to frame the Constitution of India. The Assembly was set up on 9 December 1946 and the Constitution was adopted on 26 November 1949. The Assembly met for 166 days over a period of 2 years, 11 months and 18 days. It held 11 sessions and debated 2,085 amendments to the draft Constitution. The Constitution was finally adopted on 26 November 1949 and came into effect on 26 January 1950.
Option (b) is incorrect because the Constituent Assembly took 2 years 11 months 18 days to frame the Constitution of India, not 2 years 7 months 23 days.
Option (c) is incorrect because the Constituent Assembly took 2 years 11 months 18 days to frame the Constitution of India, not 3 years 4 months 14 days.
Option (d) is incorrect because the Constituent Assembly took 2 years 11 months 18 days to frame the Constitution of India, not 3 years 11 months 5 days.