When a human female reaches the age of puberty, a sexual cycle starts which is marked by vaginal bleeding for few days at regular time interval.
Why does vaginal bleeding occur in human females on attaining puberty?

Options

A. Unfertilised egg along with thick uterus lining comes out of vagina in form of bleeding.
B. In human females, ovaries start releasing egg or ovum every 28 days from age of puberty.
C. If fertilisation does not occur then menstrual flow occurs at the end of cycle.
D. All of these

Answer

D