In the absence of fertilization, the corpus luteum . . . . . . .

Given below is a flow chart showing ovarian changes during the menstrual cycle. Fill in the spaces by providing the names of the hormones responsible for the events shown.
$\boxed{\text{Primary follicles}}$
$\downarrow \leftarrow \boxed{A}$
$\boxed{\text{Graafian follicle}}$
$\downarrow \leftarrow \boxed{B}$
$\boxed{\text{Ovum}}$
$\downarrow \leftarrow \boxed{C}$
$\boxed{\text{Corpus luteum}}$

What happens if the ovum fails to get fertilized?

Human female reaches menopause at the age of about (in $years$)

Which hormone level is required for ovulation in females?

What happens at the beginning of the menstrual cycle?