This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Physiology
[{'content': 'Smell of bitter almonds is seen in poisoning with \nSelect and explain. \nA. Phosphorus, B. Hydrocyanic acid, C. Nitric acid, D. Oxalic acid', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Cyanide can be a colorless gas, such as hydrogen cyanide (HCN) or cyanogen chloride (CNCl), or a crystal form such as sodium cyanide (NaCN) or potassiumcyanide (KCN). Cyanide sometimes is described as having a "bitter almond" smell, but it does not always give off an odor, and not everyone can detect this odor. Ref ganong\'s review of medical physiology 25e p143', 'role': 'assistant'}]