Why Air comes into the lungs as a result of the actions of the diaphragm and chest muscles which?

Air enters the lungs primarily due to the contraction of the diaphragm and intercostal muscles. When the diaphragm contracts, it moves downward, increasing the thoracic cavity's volume and creating a negative pressure relative to the atmosphere. Simultaneously, the intercostal muscles lift the ribcage, further expanding the chest cavity. This pressure difference causes air to flow into the lungs.