Option 1 is correct. The Constitution of India was framed between December 1946 and December 1949. It is important to note that the process of framing the constitution began with the appointment of the Constituent Assembly in December 1946. The drafting committee, chaired by Dr. B.R. Ambedkar, took almost three years to finalize the draft constitution.

Option 2, stating that the drafts of the Constitution were discussed in public meetings, is not mentioned in the question and thus cannot be confirmed as correct or incorrect based on the information provided.

Option 3, claiming that the Constitution of India is the shortest document of a Constitution in the world, is incorrect. In fact, the Constitution of India is one of the longest written constitutions in the world, with 395 articles, 12 schedules, and multiple amendments.

Option 4, stating that the Constitution came fully into operation immediately after the drafting was completed in December 1949, is not mentioned in the question and therefore cannot be considered as correct or incorrect based on the information provided.

In conclusion, option 1 is the correct statement about the Constitution of India.