Answer : 3. "28 February"
Explanation :

National Science Day is celebrated every year on 28 February in India. This day is celebrated all over India to give importance to the remarkable work done by Indian scientist Chandrashekhar Venkata Raman in the field of science. The theme of National Science Day 2024 is 'Indigenous Technologies for Viksit Bharat'. The first National Science Day was celebrated on 28 February 1987.