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: Biochemistry
All are involved in bilirubin metabolism except? 
Select and explain. 
A. ALA synthase, B. Heme oxygenase, C. Biliverdine reductase, D. Glucuronyl transferase
A: ALA synthase
Answer: A: ALA synthase 
Explanation: Ans. is 'a' i.e., ALA synthase