This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
An asymptomatic boy on ECG is detected to have a short P interval and delta waves. The least effective measure for the boy would be - 
Select and explain. 
A. Holter monitoring, B. Treadmill stress test, C. Beta blockers, D. Reassurance
B: Treadmill stress test
Answer: B: Treadmill stress test 
Explanation: None