The third stage of labor begins when the: Select one: a. cervix is completely dilated. b. placenta is fully delivered. c. umbilical cord has been clamped. d. baby is expelled from the vagina.

The third stage labor begins when baby is expelled from the vagina.

Explanation:

The act of expelling the baby from uterus through the vagina is called parturition.

The period of pregnancy ends with the parturition. C

Child birth occurs mainly by two methods, vaginal delivery and caesarian session.

However, Vaginal delivery is more common.

The period of labor has been divided into three stages:

During the first stage, the cervix increases and decreases in diameter, preparing for parturition.

Second stage begins with complete dilation of cervix and ends with the expulsion of baby.

Then begins the third stage that continues until the placenta is pushed out of the uterus.