Final answer:
A menstrual cycle length of 35 days is within normal limits.
Step-by-step explanation:
A) Menstrual cycle length of 20 days is not within normal limits. The average menstrual cycle length is around 28 days, but it can vary from 21 to 45 days, so a 20-day cycle would be considered shorter than average.
B) Menstrual flow lasting 7 days is within normal limits. The average menstrual period is about five days long, but it can vary from two to seven days.
C) Menstrual cramps requiring medication are not within normal limits. While some amount of discomfort or mild cramping can be normal during menstruation, severe cramps that require medication may indicate a more serious underlying issue.
D) Menstrual cycle length of 35 days is within normal limits. As mentioned before, the average menstrual cycle length is around 28 days, but it can vary from 21 to 45 days, so a 35-day cycle falls within the normal range.