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: Gynaecology & Obstetrics
Which of the following progesterones is preferred in combination with estrogen in low dose oral contraceptive pills? 
Select and explain. 
A. Desogesterol, B. Norethisterone, C. Norgesterel, D. Levonorgestrel
A: Desogesterol
Answer: A: Desogesterol 
Explanation: Low dose contraceptive pills are in recent use which contains a very minimal dose of estradiol (about 20 - 35 microgram) and desogesterol (a newer progestin). The desogesterol with a high progesteronic activity is preferred compared to the other three progestins. Ref: Textbook of Gynaecology By Rao, 183 - 184; Harrison's Endocrinology' 2nd edition, Page 199