Final answer:
The integumentary system regulates the body's temperature through thermoregulation, involving sweat secretion and blood flow regulation near the skin surface.
Step-by-step explanation:
The integumentary system plays a crucial role in various physiological functions, including protection, sensation, and metabolic processes. However, one of the key roles of this system is thermoregulation, where it maintains the body's core temperature within ideal limits. Through the action of sweat glands, which secrete sweat to cool down the body, and the regulation of blood flow near the skin surface, the integumentary system manages the loss or retention of heat in the body. Therefore, the answer to the student's question is D. Temperature. The integumentary system plays an important role in regulating the body's temperature.