This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: ECG and Arrhythmia 2, Subject name: Medicine
A 62-year-old male with underlying COPD develops a viral upper respiratory infection and begins taking an over-the-counter decongestant. Sholy thereafter he experiences palpitations and presents to the emergency room, where the given rhythm strip is obtained, demonstrating: 
Select and explain. 
A. Junctional tachycardia, B. Atrial flutter, C. Paroxysmal atrial tachycardia, D. Complete hea block
B: Atrial flutter
Answer: B: Atrial flutter 
Explanation: ECG reveals saw tooth waves of atrial flutter with variable AV block.