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
Normal duration of menstrual flow is : 
Select and explain. 
A. 2-7 days, B. 7-10 days, C. 2 days, D. 5-9 days
A: 2-7 days
Answer: A: 2-7 days 
Explanation: Duration of menstruation - 2-7 days Amount of blood loss - 20 to 50 mL with an average of 35 mL. Nearly 70 percent of total menstrual blood loss occurs in the first 2 days.