Final answer:
The most important and effective action during neonatal resuscitation is to stabilize the newborn's heart rate and respiration through chest compressions and assisted ventilation.
Step-by-step explanation:
The most important and effective action during neonatal resuscitation is to ensure that the newborn's heart rate and respiration are stabilized. Poor scores for these measurements may indicate the need for immediate medical attention. If the heart rate is low or absent, chest compressions should be initiated, and if there is inadequate or no breathing, assisted ventilation should be provided. These actions are crucial in providing oxygen to the newborn's organs and maintaining their overall well-being.