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
Which of the following inborn errors of metabolism is associated with mental retardation - 
Select and explain. 
A. Alkaptonuria, B. Homocystinuria, C. Pentosuria, D. All
B: Homocystinuria
Answer: B: Homocystinuria 
Explanation: Ans. is 'b' i.e., Homocystinuria Metabolic disorders associated with mental retardation. i) Aminoaciduria Phenylketonuria, homocystinemia, histidinemia ii) Galactosemia iii) Mucopolysaccharidosis