What are the primary organs of the integumentary system?

The primary organs of the integumentary system include the skin, nails, and hair because this system serves as the body's first line of defense against external threats and plays a crucial role in protecting internal organs.

The skin is the largest organ and acts as a barrier to pathogens, regulates temperature, and provides sensory information. Nails help protect the fingertips and improve tactile sensitivity. Hair not only provides insulation but also protects the skin from harmful UV radiation and serves as an olfactory receptor.

In contrast, the other options consist of organs that belong to different bodily systems. For instance, muscles and bones are part of the musculoskeletal system, which allows movement. The liver and pancreas are associated with the digestive system and play roles in processing nutrients and producing hormones, respectively. Lastly, the heart and lungs are critical components of the cardiovascular and respiratory systems, involved in circulation and gas exchange. Thus, the selection of skin, nails, and hair accurately represents the components of the integumentary system.