Answer : 3. "03 नवंबर"
Explanation :

Solution: In the year 2022, at the 41st session of the General Conference of UNESCO, it was decided that 3 November will be celebrated as the International Day for Biosphere Reserves across the world. Biosphere reserves are protected areas meant for the conservation of plants and animals. Humans also depend on these protected areas for their livelihood activities. There are 738 biosphere reserves in 134 countries and India has 18 notified biosphere reserves.