This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Gynaecology & Obstetrics
[{'content': 'Regarding orientation of spiral arteries, which of the following is true \nSelect and explain. \nA. Both arteries and veins are perpendicular to the uterine wall, B. Both arteries and veins are parallel to the uterine wall, C. Arteries are perpendicular and veins are parallel to the uterine wall, D. Veins are perpendicular and arteries are parallel to the uterine wall', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Spiral arteries are perpendicular and veins are parallel to uterine wall. This aids in closure of veins during a uterine contraction and prevents exit of maternal blood from intervillous space.', 'role': 'assistant'}]