The first session (meeting) of the Constituent Assembly of India was held in New Delhi on:

The first session of the Constituent Assembly of India began on 9 December 1946, in the Constitution Hall (now the Central Hall of Parliament House), New Delhi.

How the Constituent Assembly was formed:

• It was set up under the Cabinet Mission Plan of 1946.
• Its members were elected indirectly by the members of the provincial legislative assemblies, by the method of proportional representation by means of the single transferable vote.
• Seats were allotted to the provinces roughly in proportion to their population, and divided among the Muslims, the Sikhs and the general community.
• The princely states were also given seats, to be filled by their nominees.
• The elections to the seats of the British provinces were held in July-August 1946; the Congress won a large majority of the general seats, and the Muslim League won most of the Muslim seats.

The first session:

• The session was attended by more than two hundred members.
• The Muslim League boycotted the session and demanded a separate state of Pakistan.
• The princely states had not yet sent their representatives.
• The members took their seats, and the session began with the election of a temporary chairman, following the French practice of choosing the oldest member.

After partition:

After the Mountbatten Plan (3 June 1947), the members from the areas that went to Pakistan formed a separate Constituent Assembly for Pakistan.

NCERT on the Constituent Assembly:

NCERT notes that the Constituent Assembly that framed the Constitution was elected indirectly by the provincial legislatures, and that it was not elected on the basis of universal adult franchise.

Why not the other options?

• ✗15 August 1947 was the date of Independence; 26 November 1946 and 2 September 1946 were not the date of the first session.