Final answer:
The main cause of airway obstruction is asthma, which is a chronic inflammatory disease of the airways. Other causes include foreign bodies, lung cancer, and pneumonia.
Step-by-step explanation:
The main cause of airway obstruction can vary depending on the specific condition or disease. However, among the given options, the most common cause of airway obstruction is asthma. Asthma is a chronic inflammatory disease of the airways, which causes swelling and narrowing of the airways, leading to difficulty breathing. Other causes of airway obstruction include foreign bodies, such as small objects or food getting stuck in the airway, lung cancer, and pneumonia.