Which of the following is a sign or symptom of an asthma attack?

An asthma attack typically involves the narrowing of the airways, leading to difficulty in breathing. One of the hallmark signs of an asthma attack is the presence of wheezing, which is often described as a whistling or high-pitched sound that's noticeable during respiration. This wheezing is caused by the turbulent airflow through the constricted airways. Observing this sign can help differentiate an asthma attack from other respiratory issues, as it is specifically associated with the bronchospasm and airway inflammation characteristic of asthma.

While shortness of breath without wheezing can occur, it is less specific and may not be indicative of an asthma attack by itself. A rapid heart rate may accompany an asthma attack due to anxiety or decreased oxygen levels, but it does not serve as a defining symptom of the condition. Similarly, severe headache is not typically linked to asthma and could suggest other health issues, making it irrelevant in this context. Thus, whistling or high-pitched wheezing is the most recognized and defining sign of an asthma attack.