This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Physiology
Which is not synthesized by the vascular epithelium? 
Select and explain. 
A. Prostacyclin, B. Angiotensin 2, C. Endothelin, D. Heparin
B: Angiotensin 2
Answer: B: Angiotensin 2 
Explanation: Endothelial cells constitute a large and impoant tissue. They secrete many growth factors and vasoactive substances. The vasoactive substances include prostaglandins and thromboxanes, nitric oxide, and endothelins.Lungs activate angiotensin I to angiotensin II; this reaction is paicularly prominent in the lungsRef: Ganong's Review of Medical Physiology;23rd edition; Page No: 606