Which layer of the skin provides insulation and contains fat cells?

The correct answer is the hypodermis, which is the layer of skin located below the dermis. This layer is crucial for providing insulation to the body because it contains a significant amount of fat cells, also known as adipose tissue. These fat cells act as a thermal insulator, helping to regulate body temperature by reducing the heat loss from the body's core to the surrounding environment.

Additionally, the hypodermis serves other important functions, including cushioning and protecting underlying muscles and bones, as well as serving as an energy reserve. Its structure, which consists of both fat and connective tissues, allows it to be flexible while providing the necessary insulation. This explains why it is essential for maintaining warmth and energy storage in the body.