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: Pediatrics
[{'content': "A child with complaints of cough. Characteristic 'inspiratory whoop. Sample for investigation is – \nSelect and explain. \nA. Nasopharyngeal swab, B. Tracheal aspiration, C. Cough plate culture, D. Sputum culture", 'role': 'user'}, {'content': 'Answer: A \nExplanation: "Culture of nasopharyngeal secretion remains the gold standard for diagnosis of whooping cough" - Harrison', 'role': 'assistant'}]