This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: AIIMS 2017, Subject name: Medicine
Diagnosis of the following ECG- 
Select and explain. 
A. Ventricular bigeminy, B. Electrical alternans, C. P pulmonale, D. Left ventricular failure
B: Electrical alternans
Answer: B: Electrical alternans 
Explanation: Option A- Broad QRS complex with normal sinus rhythm Digoxine toxicity Option B- P wave with fluctuating QRS complexes is seen. showing ELECTRICAL ALTERANS seen in large pericardial effusion in which hea is swinging. Option C- N Height in P wave: 2.5mm But in P-pulmonale: || by 1.5mm