This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Medical, surgical and gynaecological illness complicating pregnancy, Subject name: Gynaecology & Obstetrics
[{'content': 'PIH can be prevented by \nSelect and explain. \nA. Polyhydramnios, B. Diabetes mellitus, C. Twin pregnancy, D. Smoking', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Smoking is the only environmental factor that reduces the risk of pre-eclampsia Smoking during pregnancy has adverse effects on other organs It may have effects on angiogenic factors, endothelial function and immune system reducing the risk of pre-eclampsia. Ref: Internet sources.', 'role': 'assistant'}]