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': 'In left sided massive pneumothorax, ECG shows all, except- \nSelect and explain. \nA. Left axis detion, B. Absent R wave, C. Peaked P wave, D. Precordial T wave inversion', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Abnormal left axis detion in left-sided pneumothorax. Relevant QRS abnormalities (incomplete RBBB and T-wave inversion) in(10%). QRS amplitude in V2-V6 leads was significantly decreased in left-sided pneumothorax. Ref Harrison 20th edition pg 1546', 'role': 'assistant'}]