This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Pharmacology
Serotonin is sexreted by 
Select and explain. 
A. Leukocytes, B. RBCs, C. Platelets, D. Vessel wall
C: Platelets
Answer: C: Platelets 
Explanation: platet seretonin normally the seratonin secreted from the enterochromaffin cells enters the blood stream . the platelets when bind to the clot release seratonin where it xan help in vaso constriction or dilation and hels in hemostasis Ref: Katzung 12 th ed.