Final answer:
The PRIORITY ACTION of the nurse when a mother arrives at the labor unit is to monitor fetal heart rate (B). This is essential to assess the well-being of the baby and ensure timely interventions if any concerns arise. Therefore, the correct option is B.
Step-by-step explanation:
Monitoring fetal heart rate is a critical initial step when a mother arrives at the labor unit. It provides vital information about the baby's well-being and allows the healthcare team to detect any signs of distress or abnormalities in a timely manner. Fetal heart rate monitoring helps ensure the safety of both the mother and the baby during the labor process.
Administering pain medication, checking vital signs, and preparing for delivery procedures are important aspects of care but are secondary to the immediate need of assessing the fetal heart rate.
The well-being of the baby is a top priority during labor, and continuous monitoring enables the healthcare team to make informed decisions and take prompt actions to address any complications that may arise. Therefore, monitoring fetal heart rate takes precedence as the nurse's priority action upon the mother's arrival at the labor unit.
Therefore, the correct option is B.