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
In ovarian cycle increaed levels of LH are due to 
Select and explain. 
A. Increased Progesterone, B. Increased FSH, C. Increased Androgens, D. Increased Estrogen
D: Increased Estrogen
Answer: D: Increased Estrogen 
Explanation: Luteinising Hormone 

LH is a water-soluble glycoprotein of high molecular weight secreted by beta cells of the anterior pituitary gland
LH surge initiated by estrogen lasts for 48 h. LH level doubles up in 2 hrs and peak plateaus for 14 hours before declining.
Minimum of 75 ng/ml is required for ovulation