Identify the organ circled in the image below.

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A. Decreased CO₂ and hydrogen ion concentrations and increased oxygen concentration stimulate her chemoreceptors, triggering inspiration. - Chemoreceptors respond to increased CO₂/decreased O₂.
B. The inflation reflex would not allow her to keep her lungs full of air for a prolonged period. The reflex would trigger inspiration. -The Hering–Breuer reflex prevents overinflation, not relevant here.
C. Increased CO₂ and hydrogen ion concentrations and decreased oxygen concentration stimulate her chemoreceptors, triggering inspiration. -Rising CO₂ strongly stimulates medullary chemoreceptors → involuntary breathing resumes.
D. The diaphragm will begin to fatigue and will not be able to hold its contracted position for more than a short period of time. -Breathing resumes due to chemoreceptor drive before muscle fatigue sets in.

A. Converts fibrinogen to fibrin: that reaction is carried out by thrombin, not plasmin.
B. Breaks down fibrin, dissolving the clot: plasmin is the primary enzyme of fibrinolysis, cleaving fibrin to dissolve formed clots.
C. Triggers the extrinsic clotting mechanism, leading to clot formation: the extrinsic pathway is initiated by tissue factor (factor III) interacting with factor VII, not plasmin.
D. Inactivates thrombin, slowing clot formation: plasmin’s main role is fibrin breakdown; thrombin is primarily regulated by antithrombin, thrombomodulin–protein C systems. (Plasmin can degrade some clotting proteins but it is not described as the main inactivator of thrombin.)