Final answer:
The first occurrence of menstruation is termed menarche and the menstrual cycle is ultimately controlled by GnRH.
Step-by-step explanation:
The menstrual cycle refers to natural changes that occur in the female reproductive system each month during the reproductive years. It is ultimately controlled by GnRH, a hormone produced by the hypothalamus. One of the statements about the menstrual cycle that is true is that the first occurrence is termed menarche, which refers to the first menstrual period in a female's life.