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
The production of cervical mucus is stimulated by 
Select and explain. 
A. Progesterone, B. Pregnenolone, C. Estriol, D. Estradiol
D: Estradiol
Answer: D: Estradiol 
Explanation: Cervical mucus is a glycoprotein gel that expand and contract in response to cyclic changes in the steroid hormone environment across the menstrual cycle to facilitate or inhibit the passage of sperm

Estrogen stimulates cervical mucus production, and as levels rise during the follicular phase, mucus becomes more abundant and watery, less cellular, and more easily penetrated by sperm
Progesterone inhibits cervical mucus production and renders it opaque, viscid, and impenetrable