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: Ans. is \'a\' i.e., Nasopharyngeal swab "Culture of nasopharyngeal secretion remains the gold stadard for diagnosis of whooping cough"', 'role': 'assistant'}]