Which of the following is a sign of effective compression during CPR?

A visible rise and fall of the patient's chest is a sign of effective compression during CPR because it indicates that adequate ventilation is occurring. When chest compressions are performed correctly, they generate sufficient pressure to propel blood through the circulatory system while also allowing air to flow in and out of the lungs. This physical movement of the chest is a clear indicator that the compressions are significant enough to create a change in the thoracic pressure, which is essential for effective cardiopulmonary resuscitation.

The other options do not directly indicate effective compressions. A rapid heart rate on the ECG might occur, but it doesn’t necessarily reflect the efficacy of the compressions. Abnormal breath sounds might indicate complications such as aspiration or improper ventilation but do not provide evidence regarding the chest compressions themselves. A consistent rhythm of compressions is important for maintaining quality CPR, but it doesn't confirm that the compressions are effective in achieving visible chest rise. Therefore, the visible rise and fall of the chest serves as the most direct and observable sign of effective compression during CPR.