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: Pathology
[{'content': 'Most common fixative used in electron microscopy: \nSelect and explain. \nA. Glutaraldehyde, B. Formalin, C. Picric acid, D. Absolute alcohol', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. a. Glutaraldehyde', 'role': 'assistant'}]