This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Toxicology - 2, Subject name: Forensic Medicine
[{'content': 'True about formalin \nSelect and explain. \nA. Used as preservative in alcohol poisoning, B. Never used as preservative for chemical analysis, C. Used as preservative only in digitalis poisoning, D. Used as preservative for any plant poisoning', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Formalin is not used as preservative for chemical analysis because extraction of poison becomes difficult. PRESERVATIVES : 1. Saturated solution of NaCl - commonly used 2. Rectified spirit (95% alcohol )- Best preservative 3. 10% Formalin - for histopathological examination 4. 50% Glycerol - for virology 5. NaF - For Co, Cyanide, Alcohol poisoning. Avoid salts in Avoid Rectified Spirit in 1. Corrosive except phenol 2. Aconite 1. Alcohol 2. Formalin 3. Phenol', 'role': 'assistant'}]