The correct option is C Jan 26, 1950
The Constituent Assembly adopted the Constitution of India, drafted by a committee headed by Dr. B.R. Ambedkar, on 26 November, 1949. India became a sovereign, democratic and republic after its constitution came into effect on 26 January, 1950. Dr. Rajendra Prasad became the first President of India. The three words 'socialist, 'secular' and 'integrity' were added later with the 42nd Constitution Amendment 1976.