What occurs during exhalation in relation to the diaphragm?

During exhalation, the diaphragm plays a crucial role as it relaxes and moves upwards in the thoracic cavity. This relaxation decreases the volume of the thoracic cavity and increases the pressure in the lungs, facilitating the expulsion of air. When the diaphragm is at rest or relaxed, it forms a dome shape, and this movement is essential for pushing the air out of the lungs.

Understanding the diaphragm's function is important, as it is a primary muscle involved in respiration. The contraction and relaxation of the diaphragm are key features of the breathing cycle. During inhalation, it contracts to expand the thoracic cavity volume and draw air into the lungs. In contrast, during exhalation, the diaphragm’s relaxation leads to a reduction in lung volume, allowing air to be expelled. Thus, the correct answer reflects the diaphragm's role in the breathing process during exhalation.