Final answer:
The client whose cervix is dilated to 9 cm is in the first stage of labor, which involves cervix dilation up to about 10 cm in preparation for the baby's and placenta's expulsion.
Step-by-step explanation:
The nurse identifies the client as being in the first stage of labor. There are three stages to labor: the first stage involves the cervix thinning and dilating to about 10 cm, which is necessary for the baby and placenta to be expelled during birth. The second stage is where the baby is expelled from the uterus, which includes contractions of the uterus and pushing from the mother. The last stage is the delivery of the placenta, which occurs after the baby has been born. If labor stalls before the second stage is reached, synthetic oxytocin, such as Pitocin, can be administered to maintain the progression of labor.