The correct answer is (b). The Constitution of India was adopted on November 26, 1949, and came into effect on January 26, 1950. It is the longest written constitution of any sovereign country in the world. The Constitution of India provides for a parliamentary system of government with a President as the head of state and a Prime Minister as the head of government. It also guarantees fundamental rights to all citizens, including the right to equality, the right to freedom, the right against exploitation, the right to freedom of religion, cultural and educational rights, and the right to constitutional remedies.
Option (a) is incorrect because the Constitution of India was adopted on November 26, 1949, not January 26, 1950.
Option (c) is incorrect because the Constitution of India was adopted on November 26, 1949, not February 11, 1948.
Option (d) is incorrect because the Constitution of India was adopted on November 26, 1949.