This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Biochemistry
Which of the following contains as aromatic a ring? 
Select and explain. 
A. Estradiol, B. Testosterone, C. Aldosterone, D. Coisol
A: Estradiol
Answer: A: Estradiol 
Explanation: Estradiol is the 17-beta-isomer of estradiol, an aromatized C18 steroid with hydroxyl group at 3-beta- and 17-beta-position.Ref: DM Vasudevan, 7th edition, page no: 669