In the human female, menstruation can be deferred by the administration of

Ovulation does not occur during pregnancy in the human female because

Given below is a flow chart showing ovarian changes during menstrual cycle. Fill in the spaces giving the name of the hormones responsible for the events shown.

$\boxed{\rm {Primary follicles}}$

$\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \downarrow \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \leftarrow \,\boxed A$

$\boxed{\rm {Graafian follicle}}$

$\,\,\,\,\,\,\,\,\,\,\,\,\,\, \downarrow \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \leftarrow \,\boxed B$

$\,\,\,\,\,\,\,\,\,\,\,\boxed{\rm {Ovum}}$

$\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \downarrow \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \leftarrow \,\boxed C$

$\boxed{\rm {Corpus leuteum}}$

What are the events that take place in the ovary and uterus during follicular phase of the menstrual cycle ?

During menstruation the level of progesterone in blood is