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: Radiology
A young female presents with chest pain not associated with exercise. Auscultation reveals multiple ejection clicks with a murmur. The most impoant investigation for diagnosis is: 
Select and explain. 
A. ECG, B. Thallium 201 scan, C. Tc pyrophosphate scan, D. Echocardiography
D: Echocardiography
Answer: D: Echocardiography 
Explanation: Ans. Echocardiography