Correct Option: A

World Environment Day (‘WED’) is celebrated every year on 5th June to raise global awareness of the need to take positive environmental action. It is run by the United Nations Environment Programme (UNEP). It was the day that United Nations Conference on the Human Environment began. The United Nations Conference on the Human Environment was from 5–16 June 1972. It was established by the United Nations General Assembly in 1972. The first World Environment Day was in 1973.