The First Delimitation Commission in India was set up under the Delimitation Commission Act of 1952, hence Option 4 "1952" is the correct answer.

Option 1 and 2 "1949" and "1950" are incorrect as the Delimitation Commission was not established in these years. The Constitution of India came into effect in 1950, thus there was no way a delimitation commission could be formed before that.

The third option "1951" is also incorrect, although it is the year when the first general elections were announced, but the First Delimitation Commission was set up only after this, in 1952. Therefore, this option is not the correct response.

So, the First Delimitation Commission, tasked with redrawing the boundaries of the various assembly and Lok Sabha constituencies based on a recent census, was indeed constituted only in 1952.