Estrogen is secreted by which of the following?

How many of the following statements is/are not correct?
$(a)$ Presence or absence of hymen is a reliable indicator of virginity/sexual experience.
$(b)$ Vaginal orifice is completely closed by a septum of mucous membrane called hymen.
$(c)$ The uterus opens into urethra.
$(d)$ Vagina along with cervical canal forms birth canal.

The distal narrow end of the uterus is called......

Which of the following statements is incorrect?

.......... are fleshy folds of tissue, which extend down from the mons pubis and surround the vaginal opening.

The $........$ is often torn during coitus or intercourse.