'Kokborok Day' is observed in Tripura on

In India, many observance days dedicated to a specific language, community, or state institution are fixed to the exact calendar date of the historical or administrative event they commemorate, such as the date official recognition was granted or a directorate was established, rather than to any general festival calendar. Answering such questions correctly requires recalling the specific date tied to that state or community's milestone, not simply a well-known 'days' calendar.

Kokborok is the principal language of the indigenous Tripuri community and one of the official languages of Tripura. The Government of Tripura, through its Directorate of Kokborok and Other Minority Languages, observes Kokborok Day every year on 19 January to mark the promotion and development of the language.

None of the other listed dates carries any connection to Kokborok or Tripura's language policy:

• 5th September is observed nationally as Teachers' Day, marking the birth anniversary of Dr. Sarvepalli Radhakrishnan.

• 8th March is International Women's Day, a globally observed day unrelated to any state-specific language commemoration.

• 13th February is World Radio Day, a UNESCO-designated day recognising the medium of radio, with no link to Tripura or Kokborok.

Since 19 January is the only date tied to Kokborok's recognition and promotion in Tripura, that is the date on which Kokborok Day is observed.