Explanation
Why Correct: The East Kolkata Wetlands received Ramsar site designation on August 19, 2002, under the Ramsar Convention for wetland conservation.
Distractor Analysis: Biodiversity site is a broad classification not specific to the 2002 declaration. Tourist site denotes locations developed for visitor attraction, lacking the formal conservation status. World Heritage site is a UNESCO designation for globally significant cultural or natural sites, which the East Kolkata Wetlands do not possess.
Takeaway: The Ramsar Convention, established in 1971 in Ramsar, Iran, is an intergovernmental treaty focused on wetland preservation and wise use, with over 2,400 sites worldwide.