Labor is divided into three stages first stage, second stage, and third stage. The first stage starts when a contraction starts which dilates the cervix and it ends when the cervix gets fully open.
In the second stage, the baby is pushed by the mother through the birth canal. It ends with the delivery of the baby. After the baby is born the third stage starts and the third stage ends with the separation of the placenta from the uterine wall and safely passed out through the vagina. Therefore the right answer is the third stage.