Exp) Option d is the correct answer

Option d is correct. Delimitation means the process of fixing the number of seats and boundaries of territorial constituencies in each State for the Lok Sabha and Legislative assemblies. The Union government creates the Delimitation Commission once the Delimitation Act is in effect. Under the Delimitation Acts of 1952, 1962, 1972, and 2002, Delimitation Commissions were established four times- in 1952, 1963, 1973 and 2002. The commission was not created after the 1981 and 1991 Censuses.

Source: https://forumias.com/blog/upsc-current-affairs-news/delimitation-exercise-explained-pointwise/