When did the Constituent Assembly, which framed the Indian Constitution hold its first sitting?

9 December 1946

The correct answer is Option 1- 9 December 1946 

The Constituent Assembly held its first sitting on 9 December 1946.

Formally, the Indian Constitution was made by the Constituent Assembly which had been elected for undivided India. It held its first sitting on 9 December 1946 and reassembled as Constituent Assembly for divided India on 14 August 1947. Its members were chosen by indirect election by the members of the Provincial Legislative Assemblies that had been established under the Government of India Act, 1935. The Constituent Assembly was composed roughly along the lines suggested by the plan proposed by the committee of the British cabinet, known as the Cabinet Mission.