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: Pediatrics
An infant presents with history of seizures & skin rashes. Investigations show metabolic acidosis increased blood ketone levels and normal NH3. This child is likely to be suffering from – 
Select and explain. 
A. Propionic aciduraria, B. Urea cyclic disorder, C. Phenylketonuria, D. Multiple carboxylase deficiency
D: Multiple carboxylase deficiency
Answer: D: Multiple carboxylase deficiency 
Explanation: In the degradation of valine, leucine, isoleucine (essential, branched chain aminoacids), the intermediate metabolites are all 'organic acids', and deficiency of any of the degradative enzymes (except for transminases) causes acidosis due .to accumulation of organic acids before the enzymatic block. Although most clinical manifestation are non specific, some, manifestations may provide important clues to the nature of enzyme deficiency. I have below, outlined, an approach to infants with a typical presentation, suspected of having an organic acidemia.