What are the primary mechanisms involved in the process of inhalation?

Inhalation primarily involves the contraction of the diaphragm along with the expansion of the chest cavity. When the diaphragm contracts, it moves downward, increasing the volume of the thoracic cavity. This decrease in pressure within the cavity allows air to flow into the lungs from the external environment, following the natural tendency for gases to move from areas of higher pressure to lower pressure.

Additionally, the intercostal muscles, which are located between the ribs, also contribute by contracting and raising the rib cage. This further enhances the expansion of the chest cavity, enabling a greater intake of air. Overall, this combination of diaphragm contraction and rib movement is essential for effective inhalation, facilitating adequate ventilation of the lungs.

The other options do not accurately describe the mechanics of inhalation. For example, the relaxation of the diaphragm would impede the inhalation process, and describing the lungs' expansion in terms of pressure without mentioning the essential role of the diaphragm and chest cavity doesn’t convey the full mechanism accurately.