What happens to the chest cavity when the diaphragm contracts?

When the diaphragm contracts, it moves downward and flattens out, which causes the volume of the chest cavity to increase. This increase in volume results in a decrease in pressure within the chest cavity relative to atmospheric pressure, allowing air to flow into the lungs during inhalation. The diaphragm plays a crucial role in the respiratory process by facilitating this change in pressure, which is essential for breathing. As a result, more air is drawn into the lungs, enabling oxygen intake and carbon dioxide expulsion. Therefore, the correct answer reflects the physiological process that occurs when the diaphragm contracts and its direct effect on the chest cavity volume.