The average length of a complete menstrual cycle in human females is about
- A. 14 days
- B. 21 days
- C. 28 days
- D. 35 days
Explanation
Counting from the first day of one menstruation to the day before the next gives roughly 28 days, though normal cycles vary between about 21 and 35. Fourteen days is only the average time from menstruation to ovulation.