In negative feedback for homeostasis, which statement is true?

• A. The initial change is amplified by feedback to further deviation.
• B. The system maintains a new value after disturbance.
• C. A change triggers responses to oppose it and return to set point.
• D. Negative feedback eliminates all external inputs.

Answer: (C)

Negative feedback in homeostasis works by sensing a deviation from the normal value and initiating actions that oppose that change to bring the variable back to its set point. The statement that captures this is: when a change occurs, the body triggers responses to oppose it and return to the set point. This is why temperature rises trigger cooling mechanisms (sweating, vasodilation) to bring temperature back down, and elevated blood glucose triggers insulin to promote uptake and storage to return glucose to normal levels. The other scenarios don’t describe how negative feedback maintains stability: amplification of the initial change describes a positive feedback process, not negative feedback; maintaining a new value after disturbance would imply shifting the set point rather than restoring the original point; and eliminating all external inputs isn’t accurate because external influences can cause deviations—negative feedback works to counter them rather than erase them.