Answer : 2. "22 March"
Explanation :

World Water Day is celebrated every year on 22 March with the aim of making people aware of the importance of fresh water in the world. The United Nations General Assembly adopted a resolution in December 1992 by which March 22 was declared World Water Day. In 1992, the first formal proposal for World Water Day was made under Agenda 21 at the United Nations Conference on Environment and Development in Rio de Janeiro.