This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Infectious disease, Subject name: Pediatrics
A child with complaints of cough. Characteristic inspiratory whoop. Sample for investigation is ________ 
Select and explain. 
A. Nasopharyngeal swab, B. Tracheal aspiration, C. Cough plate culture, D. Sputum culture
A: Nasopharyngeal swab
Answer: A: Nasopharyngeal swab 
Explanation: Peussis is an acute highly contagious respiratory tract infection caused by Bordetella peussis. - it is called whooping cough due to the characteristic whoop produced by the air rushing in during inspiration through half open glottis. - diagnosis is mainly based on clinical symptoms. - the sample of choice is nasopharyngeal swab. Reference : Ghai essential pediatrics, eighth edition, pg no:242,243