The correct answer is option 'C': The Cabinet Mission Plan.

The Constituent Assembly of India was established to draft the Constitution of India. It was composed of representatives from various political parties and groups, who were tasked with the responsibility of formulating the Constitution for independent India.

The composition of the Constituent Assembly was broadly based on the Cabinet Mission Plan, which was presented by a delegation of three British Cabinet ministers - Lord Pethick Lawrence, Sir Stafford Cripps, and A. V. Alexander - in 1946. The Cabinet Mission Plan aimed to address the issue of India's constitutional future and provide a framework for the transfer of power from British rule to Indian hands.

The key features of the Cabinet Mission Plan that influenced the composition of the Constituent Assembly are as follows:

1. Formation of the Constituent Assembly: The plan proposed the establishment of a Constituent Assembly, consisting of representatives from British India and the princely states, to draft the constitution for independent India.

2. Composition of the Constituent Assembly: The plan suggested that the Constituent Assembly would consist of 389 members. Out of these, 296 members were to be elected by the provincial assemblies, while the remaining 93 members were to be nominated by the princely states.

3. Representation of various groups: The plan emphasized the need for adequate representation of diverse groups in the Constituent Assembly. It recommended that the seats in the Assembly be allocated based on communal and provincial proportions, and special provisions were made to ensure representation for Scheduled Castes, Sikhs, Indian Christians, Anglo-Indians, and women.

4. Provincial Autonomy: The plan proposed the formation of an interim government at the center and in the provinces. The Constituent Assembly was to function as an elected body to work alongside the interim government and draft the constitution.

Based on these recommendations, the Constituent Assembly was constituted in November 1946. It included representatives from different political parties, princely states, and regions, ensuring a diverse and inclusive composition that reflected the aspirations and interests of the Indian people. The Assembly played a crucial role in drafting and adopting the Constitution of India, which was eventually enacted in 1950.