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: Pathology
[{'content': "Aphthous ulcers are known as - \nSelect and explain. \nA. Canker sores, B. Marjolin's ulcer, C. Curling's ulcer, D. Cushing ulcers", 'role': 'user'}, {'content': 'Answer: A \nExplanation: Aphthous ulcers \n\nAlso known as Canker Sores\nThese are superficial Ulcerations of the oral mucosa.\nThe lesions may be Single or multiple.\nUlceration is surrounded by an erythematous halo and is Covered by a thin exudate.', 'role': 'assistant'}]