(a) : Ovulation is the releasing of egg by ruptured graafian follicle. The wall of graafian follicle is ruptured by sudden increase in the level of luteinising hormone. The length of menstruation cycle is 28 days (average) from the start of one menstruation period to the start of the next. At about 14‌th ‌ day of the cycle, the distended follicle ruptures and the ovum is extruded into the Fallopian tube.