Hint:The fetal ejection reflex is the neuroendocrine reflex comprising the self-sustaining cycle of uterine contractions initiated by the pressure at the cervix or the vaginal walls. It is an example of positive feedback in biology. Parturition is the delivery of the fetus out of the uterus. It is induced by a complex neuroendocrine mechanism.
Complete answer:Normally, the human gestation period lasts for nine months, and after that vigorous contraction of the uterus results in the delivery of the fetus called parturition. The organic process is evoked by the complicated neuroendocrine mechanism and therefore the signals for this come from the absolutely developed placenta and also from the fetus. When the placenta and fetus are fully developed then it induces a mild contraction in the uterus this is called the fetal ejection reflex. Due to this positive feedback system, this mild uterine contraction triggers the release of oxytocin from the maternal pituitary, which results in stronger uterine contraction. This leads to the expulsion of the fetus out of the uterus through the birth canal. And soon after this, the placenta is cut.
Therefore, the correct answer is option D.
Note:During the pregnancy period, the mammary glands of females also undergo differentiation, and at the end of the pregnancy, it starts producing milk. This process is called lactation. In milk ejection also, oxytocin plays an important role. The milk produced during the initial days of lactation is called the colostrums which contain antibodies and proteins which is absolutely very important for infants.