Final answer:
In the immediate postpartum period, a nurse should take the client's vital signs every 15 minutes for the first hour, then every 30 minutes for the next 2 hours to monitor for any complications.
Step-by-step explanation:
In the immediate postpartum period, the recommended frequency for taking vital signs of a client who just delivered a healthy newborn is Every 15 minutes for the first hour, then every 30 minutes for the next 2 hours (Option A). This protocol helps in early detection and management of postpartum hemorrhage or other complications. After the initial period, if the client is stable, the frequency of monitoring can be adjusted based on clinical judgment and hospital policies.