Which of the following is a non-cellular layer in the Graafian follicle?

Which of the following is an incorrect statement with respect to the menstrual cycle?

Menstruation occurs due to abrupt decrease in the level of _______

Menstruation can be postponed by _______

The levels of which of the following hormone peaks around ${20}^{\mathrm{th}}$ to ${21}^{\mathrm{st}}$ day of menstrual cycle?

If the menstrual cycle of a woman is of 37 days, then the ovulation occurs on ______