Which of the following best describes the role of the skin?

The role of the skin as the body's largest organ and its function as the external protective layer is a fundamental aspect of human anatomy and physiology. The skin serves as a barrier that protects underlying tissues and organs from external threats such as pathogens, physical injury, and harmful environmental factors. It also plays a significant role in preventing water loss, thereby maintaining hydration and regulating bodily functions.

As the largest organ, the skin encompasses various structures, including hair follicles, sweat glands, and sensory receptors, which contribute to its multifunctional properties. While other options describe important functions of the skin—such as regulating body temperature, facilitating sensory perception, and energy storage—none encompass the comprehensive role of the skin in terms of size and primary protective function as effectively as the description of it being the largest organ and forming the external layer of the body. This encapsulates its critical involvement in both overall physiology and protection, setting the groundwork for other functions.