This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Physiology
Which of the following statements about Histamine is true? 
Select and explain. 
A. Is found in mast cells, B. Increases gastric acid secretion, C. Related to arousal and blood pressure, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: Histamine is a physiologically active amine, C5H9N3, found in plant and animal tissue and released from mast cells as pa of the anallergic reaction in humans. It stimulates gastric secretion and causes dilation of capillaries, constriction of bronchial smooth muscle, and decreased blood pressure.Ref: Ganong&;s review of medical physiology; 24th edition; page no: 149