Which components are found in the subcutaneous layer of the skin?

The subcutaneous layer of the skin, also known as the hypodermis, plays a critical role in providing insulation and cushioning for the body, and it is composed of various components that serve important functions. The correct answer highlights that this layer contains fat, collagen, and elastin fibers.

Fat, or adipose tissue, is a significant part of the subcutaneous layer, helping to store energy and provide insulation to maintain body temperature. Additionally, collagen and elastin fibers contribute to the structure and elasticity of the skin, allowing it to stretch and return to its original shape. This combination of components supports the skin's integrity and overall health while also facilitating the connection between the skin and underlying tissues.

In contrast, some of the other choices either omit essential components or do not accurately describe the full composition of the subcutaneous layer. For example, while muscle can be found deeper in the tissue, it is not a component of the subcutaneous layer itself. Similarly, blood vessels are present in the subcutaneous layer but are not mentioned alongside other structural components like fat and elastin fibers in the context of the subcutaneous layer's primary constituents.