World environment day coincides with commemoration of

Which of the following statements is correct? I. Montreal Protocol was signed in 1987. II. Earth Summit 1992 was held at Rio-de-Janeiro. III. World Environment Day is 5 June. IV. World Environment Day coincides with commemoration of First United Nations Conference of Human Environment. V. At DO below 4 mg/L water at normal temperature is heavily polluted.

World environment day is

World environment day is

World environment day is

World environment day is on

World environment day is on

World environment day is on