Which Scenario Is an Example of Positive Feedback

Multiple Choice

Which scenario is an example of positive feedback?

A) When oxygen levels are low, the kidneys secrete erythropoietin, which stimulates the proliferation and differentiation of red blood cells until oxygen demands are met.
B) As blood pressure increases, specialized neurons relay the change to the brainstem, which in turn, decreases the contractility of the heart and leads to vasodilation, thereby decreasing blood pressure.
C) After an injury, chemicals released at the site of injury will activate platelets, which will in turn activate additional platelets, and so on, until the clot has formed and the injury is no longer bleeding.
D) When stress levels are high, the hypothalamus secretes corticotropin-releasing hormone (CRH) , which in turn stimulates the secretion of adrenocorticotropic hormone (ACTH) , which then triggers the release of cortisol. Increased cortisol levels then inhibit the release of CRH and ACTH.
E) After eating, when glucose levels are high, insulin levels increase, leading to an increase in glycogen and fat synthesis to remove excess glucose from circulation.