This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Phenylalanine and Tyrosine metabolism Detail, Subject name: Biochemistry
Rate limiting step in catecholamine synthesis:- 
Select and explain. 
A. Phenylethanolamine N-methyltransferase, B. Dopadecarboxylase, C. Tyrosine hydroxylase, D. Tryptophan decarboxylase A
C: Tyrosine hydroxylase
Answer: C: Tyrosine hydroxylase 
Explanation: Catecholamines are epinephrine, norepinephrine and dopamine. L-DOPA is the precursor of all catecholamines The diagram given below shows the synthesis of L-DOPA and the rate limiting enzyme in the synthesis is tyrosine hydroxylase.