Answer:
A
Explanation:
Air moves down the trachea, a long straight tube in the chest. The diaphragm pulls air in and pushes it out. Behind the nasal cavity, air next passes through the pharynx, a long tube that is shared with the digestive system. Both food and air pass through the pharynx. A flap of connective tissue called the epiglottis closes over the trachea when food is swallowed to prevent choking or inhaling food. In humans, the pharynx is important in vocalization.
700,000 infected each year in the united states
