Final answer:
The demonstration of homeostasis is maintaining a constant internal body temperature, as it exemplifies the dynamic equilibrium an organism must uphold despite external changes, like fluctuating blood sugar levels.
Step-by-step explanation:
The scenario that demonstrates homeostasis is d) Maintaining a constant internal body temperature. Homeostasis is the process through which living organisms maintain a stable internal environment despite changes in their external surroundings. This constant adjustment is crucial to an organism's ability to function properly.
For example, humans maintain a body temperature close to 37°C. If the body temperature deviates from this set point, physiological mechanisms such as sweating to cool down or shivering to warm up are activated to restore balance. Similarly, when blood sugar levels rise after a meal, the body responds by releasing insulin to help lower glucose levels and maintain equilibrium within the body's systems.