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': 'Fetal bradycardia is defined as : \nSelect and explain. \nA. Less than 100 beat/min, B. Between 100 and 200 beat/min, C. Less than 120 beat/min, D. Less than 120 beat/min for a period of 15 min of continuous monitoring', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Less than 120 beat/min for a period of 15 min of continuous monitoring', 'role': 'assistant'}]