The integumentary system primarily serves as a protective barrier for the body, but none of the given options directly represent its primary functions. However, if I were to choose the best option based on common misconceptions or roles of the skin, I would say:
- absorbs water (to a limited extent, as the skin can help prevent water loss)
That said, the integumentary system's main functions include protection, regulation of body temperature, sensory perception, and the synthesis of vitamin D, among others.