Final answer:
Terbutaline therapy is considered successful when premature birth is avoided for at least 24 hours, as this medication aims to delay preterm labor.
Step-by-step explanation:
The question asks what would indicate that terbutaline therapy has been successful. Terbutaline is a medication used to delay preterm labor. It is a β2-agonist that works by relaxing smooth muscles, including those of the uterus, thereby reducing uterine contractions. When terbutaline is successful, option b) Premature birth is avoided for at least 24 hours is the most reflective of successful therapy. Avoiding premature birth gives the fetus more time to develop in utero, which can contribute to better outcomes. Options a), c), and d) are not direct indicators of the success of terbutaline in delaying labor.