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: Dental
[{'content': 'According to Horning and Cohen staging of oral\nnecrotizing diseases stage one represents \nSelect and explain. \nA. NUG, B. NUP, C. Necrotizing stomatitis, D. Noma', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]