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
[{'content': 'The amount of blood loss during each menstrual period is about: \nSelect and explain. \nA. 10 cc, B. 35 cc, C. 50 cc, D. 100 cc', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Menstrual blood is predominantly aerial, with only 25% of the blood being of venous origin. It contains tissue debris, prostaglandins, and relatively large amounts of fibrinolysin from the endometrial tissue. The usual duration of the menstrual cycle is 3-5 days. The average amount of blood loss is 30 mL. Loss of more than 80 mL is abnormal. Ref: Alford C., Nurudeen S. (2013). Chapter 4. Physiology of Reproduction in Women. In A.H. DeCherney, L. Nathan, N. Laufer, A.S. Roman (Eds), CURRENT Diagnosis & Treatment: Obstetrics & Gynecology, 11e.', 'role': 'assistant'}]