Which of the following can cause rapid-onset dyspnea?

Rapid-onset dyspnea is often associated with conditions that cause a sudden change in airflow or respiratory function. Acute bronchospasm is characterized by a sudden tightening of the muscles around the airways, leading to a quick and significant reduction in bronchial diameter. This can occur in response to various triggers such as allergens, respiratory infections, or irritants, and it can quickly lead to feelings of breathlessness due to the obstructed airflow.

In contrast, chronic bronchitis generally leads to more gradual symptoms over time as it involves long-term inflammation and mucus production in the airways. Obstructive sleep apnea is characterized by intermittent pauses in breathing during sleep, which may lead to daytime symptoms but is not typically associated with rapid-onset dyspnea. The use of asthma medication, while important for managing chronic conditions, is not a direct cause of rapid-onset dyspnea unless there is an adverse reaction or insufficient medication delivery during an acute attack.

Therefore, acute bronchospasm stands out as the condition that can lead to a sudden onset of dyspnea, making it the correct answer.