The correct option is Rajendra Prasad.
Explanation
The Constituent Assembly of India was constituted in November 1946 under the Cabinet Mission Plan. Its internal organization, including the election of its presiding officer, was established shortly after its first meeting and remained in effect during the transfer of power.
Detailed Analysis:
- The Constituent Assembly held its first meeting on December 9, 1946. Initially, Dr. Sachchidananda Sinha acted as the temporary President.
- On December 11, 1946, Dr. Rajendra Prasad was unanimously elected as the permanent President of the Constituent Assembly.
- He continued to hold this office when the Assembly met at midnight on August 14-15, 1947, assuming full sovereign powers under the Indian Independence Act, 1947.
- Dr. B.R. Ambedkar was appointed as the Chairman of the Drafting Committee later, on August 29, 1947.
- Jawaharlal Nehru took the oath as the first Prime Minister of independent India during this session but did not preside over the Assembly.
Key Takeaway: Dr. Rajendra Prasad was the President of the Constituent Assembly from December 1946 through the entire constitution-making process, including the date of Indian Independence.