Answer : 3. "Nominated by the Legislative Assemblies of various provinces"
Explanation :

The Constituent Assembly took almost three years (two years, eleven months and seventeen days to be precise) to complete its historic task of drafting the Constitution for Independent India. During this period, it held eleven sessions covering a total of 165 days. Of these, 114 days were spent on the consideration of the Draft Constitution. As to its composition, members were chosen by indirect election by the members of the Provincial Legislative Assemblies, according to the scheme recommended by the Cabinet Mission. The arrangement was: 292 members were elected through the Provincial Legislative Assemblies 93 members represented the Indian Princely States; and 4 members represented the Chief Commissioners' Provinces. The total membership of the Assembly thus was to be 389. However, as a result of the partition under the Mountbatten Plan of 3 June 1947, a separate Constituent Assembly was set up for Pakistan, and representatives of some Provinces ceased to be members of the Assembly. As a result, the membership of the Assembly was reduced to 299.