The correct answer is option 4 - Cabinet Mission. The Constituent Assembly of India was formulated based on the recommendation of the Cabinet Mission. The Cabinet Mission was sent by the British government to India in 1946, with the aim of devising a plan for the transfer of power from British rule to Indian leadership. The mission proposed the formation of a Constituent Assembly, which would be responsible for the framing of the Indian constitution. The Constituent Assembly was established in 1946 and was made up of representatives elected by the Provincial Legislative Assemblies. The Assembly worked for almost three years to draft and finalize the Indian constitution, which was finally adopted on November 26, 1949.