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': 'All of the following are features of Mobiz type I block except- \nSelect and explain. \nA. Constant PR interval, B. Normal QRS morphology, C. Regular atrial rhythm, D. Atrial rate more than ventricular rate', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Type 1 Second-degree AV block, also known as Mobitz I or Wenckebach periodicity, is almost always a disease of the AV node. ... Today, Mobitz I hea block is characterized by progressive prolongation of the PR interval on consecutive beats followed by a blocked P wave (i.e., a dropped QRS complex Ref Harrison 20th edition pg 1443', 'role': 'assistant'}]