The correct option is B 09th December, 1946
The Constitution of India was framed by a Constituent Assembly set up under the Cabinet Mission Plan of 1946. The Assembly held its first meeting on December 9, 1946, and elected Dr. Sachhidanand Sinha, the oldest member of the Assembly as the Provisional President. On December 11, 1946, the Assembly elected Dr Rajendra Prasad as its permanent Chairman.