Which organization has categorized wild flora and fauna into eight categories (the Red List), such as extinct, critically endangered and endangered?

The International Union for Conservation of Nature classifies species into the Red List's categories of threat.

UNESCO deals with education, science and heritage, not the Red List.

A conference on biodiversity is a meeting format, not the body maintaining these categories.

The Kyoto Protocol is a climate treaty unrelated to species classification.

The Red List ranks taxa from least concern through endangered to extinct.

This assessment guides conservation priorities and national wildlife policy worldwide.