Which biological process allows an organism to maintain a stable internal environment?

Homeostasis is the biological process that enables an organism to maintain a stable internal environment despite changes in external conditions. This concept is crucial for the survival of organisms, as it involves various physiological mechanisms that regulate factors such as temperature, pH, hydration, and electrolyte balance.

For example, when the body temperature rises due to external heat, mechanisms such as sweating and increased blood flow to the skin help to cool the body down. Conversely, if the body temperature drops, shivering and reduced blood flow to the skin assist in conserving heat. This constant adjustment ensures that internal conditions remain optimal for enzymatic reactions and overall function.

While regulation involves overseeing various processes within an organism, it does not specifically refer to the stability aspect emphasized in homeostasis. Adaptation pertains to evolutionary changes that occur over generations, enhancing the survival of a species rather than immediate internal stability. Metabolism involves all biochemical reactions that occur within an organism but does not specifically address the maintenance of a stable internal environment. Thus, homeostasis is the most accurate choice, as it directly relates to the ability of an organism to regulate and stabilize its internal conditions.