Which endangered language isolate, spoken by a First Nation in British Columbia's interior, has no known relation to any other language family in the world?

• A Ktunaxa ✓
• B Tlingit
• C Haida
• D Beothuk

Ktunaxa (Kutenai) is a language isolate spoken by the Ktunaxa Nation in southeastern British Columbia, with no demonstrated genetic relationship to any other language.