Please answer the following question: Answer the following question given this paragraph: Mammals conserve heat with their hair or fur. It works like the layer of insulation in the walls of a house. It traps warm air next to the skin so it can't escape into the environment. Like the squirrel in Figure below , most mammals can make their hair or fur stand up from the skin. This makes it a better insulator. Mammals also have a layer of insulating fat beneath their skin. Other vertebrates lack this layer of fat. Q: What do mammals conserve heat with? Choices: - fur or muscle - skin or bones - tendons or hair - hair or fur A:
A:
hair or fur