Final answer:
The nurse should explain that the client's cervix is opening and is 60% effaced. This indicates that the client is in the first stage of labor, where the cervix thins and dilates to prepare for delivery.
Step-by-step explanation:
The correct explanation of the client's labor progress that the nurse should give is: 'Your cervix is opening, and it is 60% effaced.' When the cervix is dilated to 4cm, this means that it has opened up 4 centimeters wide, which is part of the first stage of labor, where the cervix thins out and dilates to make way for the baby's birth. The term 'effaced' refers to the thinning of the cervix, and being 60% effaced means that the cervix has thinned out 60% of the way it needs to prepare for childbirth. During stage one, dilation and effacement occur, which is necessary for the baby and placenta to be eventually expelled during birth. As labor progresses, the cervix will eventually dilate to about 10 cm, which is considered full dilation, preparing for stage two, where the baby is expelled from the uterus.