This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Poisoning, Subject name: Forensic Medicine
[{'content': "'Phossy jaw' is seen in chronic poisoning with \nSelect and explain. \nA. Phosphorus, B. Arsenic, C. Thallium, D. Datura", 'role': 'user'}, {'content': 'Answer: A \nExplanation: PHOSPHORUS(P4 ) Chronic Poisoning: The frequent inhalation of fumes over a period of years causes necrosis of the lower jaw in the region of a decayed tooth. The vapours act on the jaw through a carious tooth or an interspace due to missing tooth where suppurative microorganisms are already present. At first there is toothache, which is followed by swelling of the jaw, loosening of the teeth, necrosis of gums, and sequestration of bone in the mandible. This condition is known as &;phossy jaw&; (glass jaw) in which osteomyelitis and necrosis of the jaw occurs, with multiple sinuses discharging foul-smelling pus. Ref:- k s narayan reddy; pg num:-551', 'role': 'assistant'}]