Which sequence correctly traces the path of air during inhalation from the nose or mouth to the site of gas exchange?

• A. Nose or mouth → pharynx → larynx → trachea
• B. Nose or mouth → trachea → bronchi → lungs → alveoli
• C. Esophagus → stomach
• D. Lungs → bronchi → alveoli → trachea

Answer: (B)

Air enters the body through the nose or mouth and travels down the airway to reach the lungs, where gas exchange happens at the alveoli. The main path shows the trachea as the conduit that leads into the bronchi, which carry air into the lungs and finally deliver it to the tiny air sacs called alveoli. This progression—trachea, bronchi, lungs, alveoli—best matches the route from entry to the site of gas exchange. The other options either stop too early (not reaching the gas-exchange site), mix in digestive structures (esophagus), or place the components in the wrong order (air travels through the trachea and bronchi before reaching the lungs and alveoli).