The correct option is B 26 November, 1949
The Constitution of India came into force on 26 January 1950. The
Constitution Assembly set up a Drafting Committee under the Chairmanship
of Dr. B. R. Ambedkar on 29 August, 1947 to prepare a Draft
Constitution for India. The Constitution of India was adopted by the
Constituent Assembly on 26 November 1949 and came into force on 26
January 1950.