The correct option is A Foetal ejection reflex
Parturition is an induced complex neuroendocrine mechanism. In this, signals originate from a fully developed foetus and placenta. This leads to mild uterine contractions called foetal ejection reflex. Then, oxytocin is released from maternal pituitary and it acts on uterine muscles leading to strong uterine contractions. This further continues to stronger and stronger contractions leading to child birth.