This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General obstetrics, Subject name: Anatomy
[{'content': 'Which of the following trigger onset of labour? \nSelect and explain. \nA. ACTH in mother, B. ACTH in fetus, C. Prostaglandin, D. Oxytocin', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Fetal ACTH acts on fetal adrenal gland causing release of DHEA and DHEA sulphate which are used by the placenta along with the other enzymes like Sulfatase ,Aromatase, 3 B hydroxysteroid dehydrogenase, 17 B hydroxysteroid dehydrogenase -Conveing into Estriol and Estardiol that help in triggering the labour. Ref: Williams Obs 24e pg 108-109.', 'role': 'assistant'}]