Which of the Following Is a CORRECT Statement About the Menstrual

Which of the following is a CORRECT statement about the menstrual cycle?

A) Ovulation does not have to occur in every menstrual cycle,especially for girls in puberty and older women.
B) Almost all women come quite close to approximating the "perfect" 28 day menstrual cycle.
C) There is relatively little variation between women on the length of the menstrual cycle and the timing of ovulation.
D) The luteal phase of the menstrual cycle is the most constant;it is almost always about 10 days from ovulation to menstruation.