During the process of exhalation, which of the following occurs?

During exhalation, the diaphragm moves upwards as it relaxes. This upward movement decreases the volume of the thoracic cavity, which in turn increases the pressure within the lungs, allowing air to be expelled from the respiratory system. This process is a fundamental aspect of how respiration functions—when the diaphragm contracts during inhalation, it moves downwards, creating a negative pressure that allows air to flow into the lungs. On the other hand, during exhalation, the relaxation of the diaphragm and the subsequent upward movement are crucial for pushing air out.

The other choices do not accurately describe the physiological changes that occur during exhalation. The ribs do not move outward during this phase; rather, they typically move inward as the intercostal muscles relax. Additionally, air is not inhaled through the nose during exhalation; this describes the inhalation phase instead. Therefore, the upward movement of the diaphragm is critical for understanding the mechanics of breathing, particularly during exhalation.