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: Forensic Medicine
[{'content': 'Preservative used for toxicological specimen - \nSelect and explain. \nA. 20% formalin, B. Saturated sodium chloride, C. 20% alcohol, D. 10% alcohol', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Saturated salt solution\xa0→ All poisons including carbolic acid, but excluding other acids.\nRectified spirit\xa0→ Poisoning with all acids except carbolic acid.', 'role': 'assistant'}]