Which of the following hormone levels will cause release of ovum (ovulation) from the Graafian follicle?

High levels of oestrogen around midcycle of the menstrual cycle stimulate an increase in GnRH pulse frequency. This leads to the release of LH. The LH surge stimulates ovulation. 

(2) Progesterone levels are very low at the time of ovulation. High progesterone levels stimulate a decrease in GnRH pulse frequency.

(3) LH surge (high concentration) triggers ovulation. 

(4) FSH levels are high at the time of ovulation.