Which extinct language isolate, formerly spoken by Native peoples in what is now Louisiana and East Texas, is one of the few North American indigenous languages that linguists have definitively been unable to classify?

• A Tunica
• B Atakapa ✓
• C Chitimacha
• D Natchez

Atakapa (Ishak) was spoken on the Gulf Coast and is documented only in vocabulary lists collected in the 18th and 19th centuries; the last fluent speakers died in the early 20th century.