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: ENT
[{'content': 'The commonest cause of U/L mucopurulent rhinorrhoea in a child is - \nSelect and explain. \nA. Foreign body, B. Adenoids which are blocking the airways, C. Deviated nasal septum, D. Inadequately treated acute frontal sinusitis', 'role': 'user'}, {'content': 'Answer: A \nExplanation: "A unilateral nasal discharge is nearly always due to a foreign body and if the discharge has an unpleasant smell, it is\xa0pathognomonic".\xa0— Logan Turner 10th/e p. 63\n"If a child presents with unilateral, foul smelling nasal discharge, the foreign body must be excluded".\xa0— Dhingra 5th/e p. 176', 'role': 'assistant'}]