Negative feedback counteracts changes to maintain homeostasis

Steps:

• Recall negative feedback definition: a response that opposes the initial stimulus to restore balance.
• Check each option for opposition to the change versus amplification or unrelated effects.
• Eliminate options showing amplification (positive feedback) or neutral loops.
• Identify the option where high stimulus triggers a reducing response.

Why D is correct:

• It matches negative feedback by describing how high blood pressure triggers vessel dilation, which lowers pressure back to normal levels.

Why the others are wrong:

• A describes positive feedback, as platelet activation amplifies clotting.
• B shows negative feedback in hormone regulation but is specific to reproductive cycles, not general control.
• C depicts a positive loop where CO2 increase boosts photosynthesis without opposition.

Final answer: D