This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Osteoporosis, Sex Hormones and OCPs, Subject name: Pharmacology
The estrogen that is used in most combined hormonal contraceptives is: 
Select and explain. 
A. Clomiphene, B. Ethinyl estradiol, C. Estrone, D. Norgestrel
B: Ethinyl estradiol
Answer: B: Ethinyl estradiol 
Explanation: -Most commonly used estrogen in OCPs is ethinyl estradiol. -Most commonly used progesterone in OCPs is levonorgestrel.