Why should lineups be conducted by investigators who do not know much about the case?

A5-year-old boy suddenly begins coughing while eating peanuts. he is choking and gagging. when he is brought to the ed, but he is awake and is able to give his name. on physical examination, his vital signs are stable. on examination of the chest, inspiratory stridor and intercostal and suprasternal retractions are apparent. which of the following is the most appropriate initial step in management? - allow patient to clear foreign object by spontaneous coughing- clear oropharynx with multiple blind sweeps with finger- position patient and perform back blows- stand behind patient and perform abdominal thrusts- perform emergency tracheostomy and take to surgery