Menstrual cycle include 4 phases(Menstrual, Folecular, ovulatory and secretory).
The question asks for the time duration in which ovulation takes place. It take place in ovulatory phase. Ovulation refers to rupturing of graffian follicle n release of ovum (in general term). This occur due to increase in LH secretion(to a very high value). This is called LH Surge and this occur in 14th day of menstruation cycle.