The correct answer is C. 28 days
Step-by-step explanation:
The menstrual cycle includes a set of different changes and processes that occur every month in the body of women and that involves the reproductive system of women and the production of ovules (female reproductive cells). This natural cycle ideally lasts 28 days and includes four main stages; these are the menstruation, follicular phase, ovulation, and the luteal phase. However, in some women, this cycle lasts more or less because this can be affected by different conditions or external changes. According to this, the correct answer is 28 days because the ideal duration of the menstrual cycle is 28 days or four weeks.