May 21 in India is observed as National Anti-Terrorism Day. This day is observed to raise awareness about the impact of terrorism on society and to promote unity against the threat of terrorism. It aims to spread the message of peace, harmony, and tolerance among people.
Option 1: NRI Day is incorrect. NRI (Non-Residential Indian) Day is celebrated on January 9th to honor the contributions of overseas Indians.
Option 2: National Youth Day is incorrect. National Youth Day is celebrated on January 12th to commemorate the birth anniversary of Swami Vivekananda, who was a great thinker and a youth icon.
Option 3: National Technology Day is incorrect. National Technology Day is observed on May 11th to highlight the achievements of Indian scientists and engineers in the field of technology.
Therefore, the correct answer is option 4: National Anti-Terrorism Day.