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: Anatomy
[{'content': 'Muscle used for inspiration during quite breathing: \nSelect and explain. \nA. Diaphragm, B. Rectus abdominis, C. Sternocleidomastoids, D. Scaleni', 'role': 'user'}, {'content': "Answer: A \nExplanation: DiaphragmIt is crucial for breathing and respiration.It's responsible for 45% of the air that enters the lungs during quiet breathing.During inhalation, the diaphragm contracts, thus enlarging the thoracic cavity (the external intercostal muscles also paicipate in this enlargement).This reduces intra-thoracic pressure: in other words, enlarging the cavity creates suction that draws air into the lungs.When the diaphragm relaxes, air is exhaled by elastic recoil of the lung and the tissues lining the thoracic cavity in conjunction with the abdominal muscles which act as an antagonist paired with the diaphragm's contraction.", 'role': 'assistant'}]