Question

multiple choice question
antithrombin is a plasma protein produced by the liver that works to deactivate what?

○ heparin
○ histamine
○ thrombin

Explanation:

Antithrombin is a protein that functions to inactivate thrombin (a key enzyme in the blood - clotting process). Heparin is a substance that enhances the action of antithrombin, and histamine is involved in allergic responses and inflammation, not related to antithrombin's target. So the correct option is the one related to thrombin.

Answer:

C. Thrombin (assuming the options are labeled A. Heparin, B. Histamine, C. Thrombin; if the original labels are different, adjust accordingly based on the option with "Thrombin")