This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Disorders of Amino acid Metabolism, Subject name: Pediatrics
Nitroprusside test is done for the diagnosis of which of the following diseases? 
Select and explain. 
A. Phenylketonuria, B. Tyrosinemia, C. Maple syrup urine disease, D. Homocystinuria
D: Homocystinuria
Answer: D: Homocystinuria 
Explanation: Nitroprusside test- for Homocystinuria Ferric chloride test- for Phenylketonuria Dinitrophenylhydrazine test- for Organic acidemia/ Maple syrup urine disease