<prompt> Hypopnea is defined as?10 reduction in airflow for at least 10 seconds with 1 desaturation on arousal20 reduction in airflow for at least 10 seconds with 2 desaturation on arousal30 reduction in airflow for at least 10 seconds with 3 desaturation on arousal40 reduction in airflow for at least 10 seconds with 4 desaturation on arousal  <response>: Hypopnea is defined as 30 reduction in airflow for at least 10 seconds with 3 desaturation on arousal. 