Answer : 3. "20th March"
Explanation :

Answer: C) 20th March Explanation: The International Day of Happiness (known as Happiness Day) is celebrated throughout the world on the 20th of March. The International Day of Happiness was founded on June 28, 2012, by the United Nations General Assembly when all 193 member states unanimously adopted UN resolution 66/281. It was celebrated for the first time in 2013.