Which of the following is a sign of airway obstruction?

Noisy breathing is indeed a key indicator of airway obstruction. When there is an obstruction in the airway, whether partial or complete, the airflow is disrupted, which can lead to various abnormal sounds during breathing. These sounds can include wheezing, stridor, or gurgling, depending on the location and cause of the obstruction. Noisy breathing signifies that there is some level of obstruction preventing smooth airflow, which is crucial in assessing a person's airway status.

In contrast, clear lung sounds typically indicate that the airways are unobstructed and that air is moving freely through the lungs, which does not align with the signs of obstruction. The absence of distress is also inconsistent with airway obstruction since a patient experiencing an airway blockage is likely to show signs of anxiety or discomfort due to the inability to breathe normally. Lastly, a low respiratory rate may occur for various reasons but does not directly indicate an obstruction; in fact, it might suggest hypoventilation or other respiratory issues that need further investigation. Therefore, noisy breathing stands out as the most telling sign of an airway obstruction.