The correct option is 2 and 3 only.
Explanation
The timeline of the Indian Constitution involves distinct milestones regarding the formation of the Constituent Assembly, the adoption of the text, and its final enforcement as the supreme law of the land.
Statement 1 is Incorrect: The Constituent Assembly held its first sitting on December 9, 1946. While the Indian Independence Act, 1947, made the Assembly a fully sovereign body on August 15, 1947, the Assembly had already been functioning prior to independence under the Cabinet Mission Plan.
Statement 2 is Correct: The Constitution was adopted, enacted, and given to the people of India on November 26, 1949. This date is explicitly mentioned in the Preamble. Certain provisions regarding citizenship, elections, and the provisional parliament came into force immediately on this date.
Statement 3 is Correct: The Constitution came into full force on January 26, 1950. This date is referred to as the "date of its commencement" and was chosen to commemorate the Purna Swaraj declaration of 1930.
Key Takeaway: It is crucial to distinguish between the Date of Adoption (November 26, 1949) and the Date of Commencement (January 26, 1950).