[B] There was an array of disagreements with the Cabinet Mission amongst the different sections in India and formation was Constituent Assembly by directly elected members was not possible.
[C] The People of India had already given a mandate to create a Constituent Assembly from the elected members of Legislatures of various provinces
[D] The Princely states had objected for direct elections for the members of the Constituent assembly
When the Labor Government under Clement Atlee came under power in 1940s, there was a change in the Indian policy of Britain. The government of Clement Atlee had appointed the Cabinet Mission to look into the matter of Constituent assembly for India. There was an array of disagreements with the Cabinet Mission amongst different sections of India and this was the primary reason that the formation of Constituent assembly by directly elected members was not possible. Since, Jinnah and the Muslim league wanted two Constituent assemblies one for India and one for Future Pakistan, it was decided that the a Constituent assembly is to be formed by the newly elected legislators of the Provincial assemblies. Thus, based upon this premise, the provinces were grouped into three regions viz. Predominantly Hindu, Predominantly Muslim and those where both were almost equal in number. The members of Constituent assembly were elected accordingly and it was boycotted by Jinnah et al.