This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Abnormal labor, Subject name: Gynaecology & Obstetrics
[{'content': 'Post-term labour is seen in: \nSelect and explain. \nA. Hydramnios, B. PID, C. Anencephaly, D. Multiple pregnancy', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Post term labour is seen in anencephaly. Pituitary is absent. It interfers with hormonal control of onset of labour. TEXTBOOK OF OBSTETRICS, SHEILA BALAKRISHNAN, 2nd EDITION,pg:218', 'role': 'assistant'}]