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
Echocardiography can detect pericardial effusion as little as: 
Select and explain. 
A. 15 ml, B. 100 ml, C. 150 ml, D. 200 ml
A: 15 ml
Answer: A: 15 ml 
Explanation: Ans.