The correct answer is: A. National Science Day
National Science Day is celebrated in India every year on 28 February to commemorate the discovery of the Raman Effect by Indian physicist Sir Chandrasekhara Venkata Raman on 28 February 1928. The Raman Effect is the scattering of light by a substance, and the change in the wavelength of the scattered light as a result of the interaction with the substance. Raman was awarded the Nobel Prize in Physics in 1930 for his discovery.
National Science Day is a day to celebrate the achievements of Indian scientists and to promote science education and awareness among the public. It is also a day to reflect on the importance of science in our lives and to consider how we can use science to solve the challenges facing our world.
The other options are incorrect because:
- National Hindi Diwas is celebrated on 14 September.
- National Youth Day is celebrated on 12 January.
- National Voters Day is celebrated on 25 January.