Step 1: Recall which convention deals with wetlands.
Among international environmental treaties, one is specifically dedicated to protecting wetlands because of their ecological value.
Step 2: Recall its background.
It was adopted in the Iranian city of Ramsar in 1971, and that is where it gets its name, and it lists wetlands of international importance for conservation.
Step 3: Eliminate the others.
Bonn deals with migratory species, Vienna with the ozone layer, and Nagoya with genetic resources, so wetlands point clearly to Ramsar.
\[ \boxed{\text{Ramsar Convention}} \]