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
Which of the following urinary metabolites are most sensitive for diagnosis of pheochromocytomas 
Select and explain. 
A. VMA, B. Metanephrines, C. 5HIAA, D. 5HTP
B: Metanephrines
Answer: B: Metanephrines 
Explanation: Answer is B (Metanephrines): The most sensitive test for diagnosis of pheochromocytomas is measurement of fractionated metanephrines in urine and free metanephrines in plasma.