This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S, Subject name: Medicine
[{'content': 'Which of the following abnormality is seen in first-degree hea block? \nSelect and explain. \nA. PR interval >140ms, B. PR interval >160ms, C. PR interval >180ms, D. PR interval >200ms', 'role': 'user'}, {'content': 'Answer: D \nExplanation: First-degree AV block (PR interval >200 ms) is a slowing of conduction through the AV junction. All p waves will be followed by QRS complexNormal PR interval 120-200msHarrison 19e pg: 1472', 'role': 'assistant'}]