Answer : 3. "26 January 1950"
Explanation :

1. The Constituent Assembly passed the Constitution of India on November 26, 1949, but it came into force on January 26, 1950. India came into existence as a Republic on January 26, 1950.

2. The Constituent Assembly was established on December 9, 1946, to frame the Constitution of India. There were a total of 389 members in the Constituent Assembly, out of which 299 members were from the Indian National Congress. The Constituent Assembly drafted the Constitution in 2 years, 11 months and 18 days.

3. The Constitution of India is a written constitution. It is the longest-written constitution in the world. It consists of 395 articles, 8 schedules and 12 schedules. The Constitution sets out the structure, powers and functions of the Government of India. It also ensures the rights and freedoms of the citizens.