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: Medicine
[{'content': 'Adam stokes syndrome is caused due to: \nSelect and explain. \nA. Atrial fibrillation, B. Atrial extrasystole, C. Complete AV block, D. Ventilation fibrillation', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]