A、They lived in large groups. B、They used sand as insulation. C、They kept fires burning constantly. D、They faced their homes tow

M: Hey, Jane! What’s so interesting?
W: What? Oh, hi, Tom! I’m reading this fascinating article on the societies of the Ice Age during the Pleistocene period.
M: The Ice Age? There weren’t any societies then--just a bunch of cave people.
W: That’s what people used to think. But a new exhibit at the American Museum of Natural History shows that Ice Age people were surprisingly advanced.
M: Oh, really? In what ways?
W: Well, Ice Age people were the inventors of language, art, and music as we know it.  And they didn’t live in caves; they built their own shelters.
M: What did they use to build them? The cold weather would have killed off most of the trees, so they couldn’t have used wood.
W: In some of the warmer climates they did build houses of wood. In other places they used animal bones and skins or lived in natural stone shelters.
M: How did they stay warm? Animal-skin walls don’t sound very sturdy.
W: Well, it says here that in the early Ice Age they often faced their homes toward the south to take advantage of the sun—a primitive sort of solar heating.
M: Hey, that’s pretty smart.
W: Then people in the late Ice Age even insulated their homes by putting heated cobblestones on the floor.
M: I guess I spoke too soon. Can I read that magazine article after you’re done? I think I’m going to try to impress my anthropology teacher with my amazing knowledge of Ice Age civilization.
W: What a show-off!