This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Basic Concepts, Subject name: Pathology
Which of the following is the most common fixative used in electron microscopy? 
Select and explain. 
A. Glutaraldehyde, B. Formalin, C. Picric acid, D. Absolute alcohol
A: Glutaraldehyde
Answer: A: Glutaraldehyde 
Explanation: Commonest fixative used for light microscopic examination: 10% buffered neutral formalin. Commonest fixative used for electron microscopic examination: Glutaraldehyde.