This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Normal Menstruation, Abnormal Menstruation, Menopausal Physiology and forsight of conception, Subject name: Gynaecology & Obstetrics
Ovulation is seen after how many hours of the 'Peak' of the 'Up stroke' in this diagram here : 
Select and explain. 
A. 0-6 hours, B. 10-12 hours, C. 12-24 hours, D. 24-36 hours
B: 10-12 hours
Answer: B: 10-12 hours 
Explanation: From the onset of the LH surge, it takes 34-36 hours and from the peak it takes 10-12 hours to ovulate. The midcycle LH surge is responsible for a dramatic increase in local concentrations of prostaglandins and proteolytic enzymes in the follicle. These substances progressively weaken the follicular wall and ultimately allow a perforation to form.