Option 1 is the correct answer.

The Preamble begins with the words “We the people of India…” Thus, it is clearly indicating the source of all authority of the constitution. Hence, option (4) is the correct answer.

The main function of the 'Constituent Assembly' was framing the constitution.

Correct Answer: November 26, 1949

The Indian Constitution was adopted by the Constituent Assembly on  26^th November, 1949

Correct answer is (3). 

The Constituent Assembly of India was elected to write the constitution of India and after independence, served as the nation's first parliament. The Union Constitution Committee, formed by the Constituent Assembly, was headed by Jawaharlal Nehru. Jawaharlal Nehru became a leader of the left wing of the Congress when fairly young. 

Option (2) is the correct answer. 

The idea of a Constituent Assembly to frame the Constitution for India was mooted in 1928.

Sardar Vallabhbhai Patel and V. P. Menon convinced the rulers of various princely states to accede to India through a combination of factors.

The National Commission headed by Justice Shri M.N. Venkatachaliah, to review the working of the Constitution, was set up to find out how the Constitution can respond to the changing needs of efficient, smooth and effective system of governance and socio-economic development of modern India within the framework of Parliamentary democracy, and to recommend changes, if any, that are required in the provisions of the Constitution without interfering with its basic structure or features.

Correct Answer: B. N. Rau