This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
[{'content': 'Histamine is mainly found within storage granules of mast cells but also found in other tissues like: \nSelect and explain. \nA. Gastric mucosa., B. Oral mucosa., C. Inner epithelium., D. All of the above.', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Histamine is mainly found within storage granules of mast cell but also found in other tissue \n\nMast cell histamine – mast cell and basophile. \nNon mast cell histamine – Gastric mucosa.', 'role': 'assistant'}]