Menstrual flow occurs due to lack of

The following graph shows the relative concentrations of the four hormones present in the blood plasma of a woman during her menstrual cycle. Identify the hormones.

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.
$\boxed{\text{Primary follicles}}$
$\downarrow \leftarrow \boxed{A}$
$\boxed{\text{Graafian follicle}}$
$\downarrow \leftarrow \boxed{B}$
$\boxed{\text{Ovum}}$
$\downarrow \leftarrow \boxed{C}$
$\boxed{\text{Corpus luteum}}$

Identify the hormones $A, B, C$ and $D$ from the graph by observing their concentrations in blood during the menstrual cycle of a female:

Which hormone is produced throughout the menstrual cycle?

If in a normal menstruating woman,menses occur on $5^{\text{th}}$ April,what will be the expected date of ovulation?