The maintenance of a stable internal environment within the body of a mammal is known as

Step 1: Analyze the question The question asks for the term used for keeping the body's internal conditions (temperature, water level, blood sugar, pH, etc.) stable in a mammal.

Step 2: Explain the concept Mammals are warm-blooded and must keep their internal conditions within a narrow range so that cells and enzymes can work properly. Examples include:

• Body temperature, kept at about 37°C by sweating, shivering and vasodilation or vasoconstriction.
• Blood sugar level, controlled by insulin and glucagon.
• Water and salt balance, controlled by the kidneys and ADH.

This overall process is called homeostasis. The word comes from "homeo" (similar or steady) and "stasis" (state).

Step 3: Check each option

• A. Osmosis: the movement of water from a region of high water potential to one of low water potential through a semi-permeable membrane. It is a physical process, not the maintenance of the whole internal environment.
• B. Plasmolysis: the shrinking of a plant cell's protoplasm away from the cell wall when the cell loses water in a concentrated solution. It has nothing to do with stability in mammals.
• C. Homeostasis: the maintenance of a constant internal environment. This matches the question exactly.
• D. Excretion: the removal of metabolic waste products such as urea and CO₂. It contributes to homeostasis but is only one part of it.

Step 4: Answer The correct answer is C. homeostasis.

Tip: Link "homeo" with "home": your body keeps its "home" (internal environment) steady. Also remember that excretion and osmoregulation are parts of homeostasis, while homeostasis is the whole concept.