Some of the oldest known cave paintings are located in...

Lascaux
Altimira
Both A & B
Mesopotamia

The correct answer is Lascaux. Lascaux is a complex of caves located in southwestern France. The cave paintings found there are considered some of the oldest and most well-preserved examples of prehistoric art. If you're wondering how to find the answer to such a question, you can conduct an internet search or refer to historical resources that specialize in prehistoric art or archaeology. Such resources might include books, academic journals, or reputable websites dedicated to the subject.