This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of protein and amino acid, Subject name: Biochemistry
Ferric chloride test in PKU gives 
Select and explain. 
A. Green, B. Red, C. Yellow, D. Blue
A: Green
Answer: A: Green 
Explanation: Urine of the patient contains phenylketones about 500- 3000 mg/day . This could be detected by adding a drop of ferric chloride to the urine . A transient blue - green color is a positive test. But this is a less reliable test. Ref : DM.VASUDEVAN.TEXTBOOK ; SEVENTH EDITION ; PAGE NO : 237.