Which of the following pulls air into the body during inspiration?

The diaphragm plays a crucial role in the process of inspiration, which is the act of drawing air into the lungs. When the diaphragm contracts, it moves downward, creating a negative pressure in the thoracic cavity. This negative pressure allows air to be pulled into the lungs through the respiratory tract.

During inspiration, the diaphragm is the primary muscle involved, and its contraction increases the volume of the thoracic cavity. This expansion of the cavity reduces the pressure inside compared to the atmospheric pressure, causing air to flow into the lungs through the trachea and bronchi.

While other structures like the trachea and bronchioles are important for conducting air, they do not actively pull air into the body; rather, they serve as pathways for the air that has been drawn in. The pleura, which are membranes surrounding the lungs, help in reducing friction during breathing but do not contribute to the act of inspiration directly. Therefore, the diaphragm is correctly identified as the muscle that pulls air into the body during the process of breathing in.