What happens to the diaphragm when we inhale?

When we inhale, the diaphragm contracts and moves downwards. This action increases the volume of the thoracic cavity, lowering the internal pressure relative to the atmospheric pressure outside the body. As a result, air is drawn into the lungs due to this difference in pressure, which is essential for respiration. The contraction of the diaphragm is a key component of the process of inhalation, facilitating efficient breathing.

The other options do not accurately describe the mechanics of inhalation. For instance, if the diaphragm were to relax and move upwards, it would decrease the volume of the thoracic cavity, making inhalation impossible. A neutral position would not affect the lung volume or air flow during breathing, and simply contracting and expanding does not accurately describe the diaphragm's movement in the context of inhalation.