This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Toxicology, Subject name: Medicine
[{'content': 'On exposure to air, urine colour changes to olive green in poisoning with: (PGI June 2008) \nSelect and explain. \nA. Carbolic add, B. Cyclophosphamide, C. Phenopthalein, D. Ethelene glycol', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans.: A (Carbolic acid poisoning) "Carbolic acid (phenol) poisoning urine may be colorless or slightly green at first but turns green\'-1 or even black on exposure to air"- Reddy 27thf470Carbolic acid0|Oxidation|Oxidation (metabolism in body)|Hvdroquinone & pvrocatechol|Excreted in urine|Further oxidation|Green colour of Urine (carboluria)Q', 'role': 'assistant'}]