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
Rate limiting enzyme in catecholamine synthesis? 
Select and explain. 
A. Dopa decarboxylase, B. N-methyltransferase, C. Dopamine hydroxylase, D. Tyrosine hydroxylase
D: Tyrosine hydroxylase
Answer: D: Tyrosine hydroxylase 
Explanation: Ans. is 'd' i.e., Tyrosine hydroxylase