This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Reproductive physiology and hormones in females, Subject name: Gynaecology & Obstetrics
In ovarian cycle increased levels of LH are due to : 
Select and explain. 
A. Increased Progesterone, B. Increased Estrogen, C. Increased FSH, D. Increased Androgens
B: Increased Estrogen
Answer: B: 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 Ref: Shaw's Textbook of Gynaecology, 16th edition, page no: 39