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 hormone responsible for a positive "Fern test" is : 
Select and explain. 
A. Estrogen, B. Progesterone, C. FSH, D. LH
A: Estrogen
Answer: A: Estrogen 
Explanation: Estrogen