In ovarian cycle increaed levels of LH are due to: (A) Increased Progesterone, (B) Increased FSH, (C) Increased Androgens, (D) Increased Estrogen
Answer is D. 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