This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Enzymes, Subject name: Biochemistry
Which enzyme converts androgen to estrogen?- 
Select and explain. 
A. Cholesterol Desmolase, B. Aromatase, C. 11 b hydroxylase, D. 21 b hydroxylase
B: Aromatase
Answer: B: Aromatase 
Explanation: Ans. is 'b' i.e., Aromatase* Aromatase is an enzyme located in the endoplasmic reticulum of gonads, adipose tissue and placenta* It helps in the conversion of androgen into estrogen. It converts androstenedione to estrone and testosterone to estradiol* This conversion is done by three successive hydroxylation and by removal of methyl group as formate and by aromatization of the A ring