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
The normal P wave is biphasic in lead 
Select and explain. 
A. V1, B. LII, C. aVF, D. aVR
A: V1
Answer: A: V1 
Explanation: The normal P wave in lead V1 may be biphasic with a positive component reflecting right atrial depolarization, followed by a small (<1 mm2 ) negative component reflecting left atrial depolarization. Ref Harrison 20th edition pg 1455