This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory System Pa 1, Subject name: Physiology
[{'content': "Which among the given options would produce most negative intrathoracic pressure? \nSelect and explain. \nA. Yawning, B. First cry of a neonates, C. High pitch opera singing, D. Muller's manoeuvre", 'role': 'user'}, {'content': "Answer: D \nExplanation: Under quiet breathing - At sta of inspiration normal ITP - -5 cm H2O At the end of inspiration normal ITP - -7 cm H2O Forceful breathing ITP: - * deep sigh or a yawn- 30 cm H2O First cry of a neonate, (first breath ITP) - -60cmH2O Muller's maneuver - 100cm H2O Max negative ITP It is counter pa of Valsalva maneuver Muller maneuver is forced inspiratory effo against a closed glottis.", 'role': 'assistant'}]