Stridor.

• A. Wheezing
• B. Rales
• C. Stridor
• D. Bradypnea

Answer: (C)

Stridor is a harsh, high-pitched sound caused by turbulent airflow through a narrowed upper airway, usually heard during inspiration. This points to obstruction or swelling above the vocal cords, such as in laryngeal edema, croup, epiglottitis, or a foreign body. It differs from wheezing, which is a musical whistling sound from narrowed lower airways (bronchi/bronchioles) and is typically more pronounced during expiration. Rales are crackling sounds arising from fluid in the small airways or alveoli and are not related to upper airway obstruction. Bradypnea means a slow breathing rate, not an audible sound. Because stridor signals upper airway narrowing, recognizing it highlights potential airway compromise and the need for careful assessment and possible urgent management.