The correct answer is (a).
The Hindi version of the National Anthem, Jana-Gana-Mana, was adopted by the Constituent Assembly of India on 26 November, 1949. The song was originally written in Bengali by Rabindranath Tagore in 1905. It was first sung at the Calcutta session of the Indian National Congress in 1906. The song became popular as a national anthem during the Indian independence movement. After India’s independence in 1947, the Constituent Assembly adopted the Hindi version of the song as the national anthem of India.
The other options are incorrect. Option (b) is the date on which the Constitution of India was adopted. Option (c) is the date on which India became a republic. Option (d) is the date on which the Constituent Assembly was formed.