The average hormonal pill pack is designed for a 28 day cycle. Which of the following statements is/are true?
I. Hormonal pills are taken for 3 weeks, and no pills are taken for the next 1 week.
II. Hormonal pills are taken for 2 weeks, and no pills are taken for the next 2 weeks.
III. Hormonal pills are taken for 3 weeks, and non hormonal pills for the next 1 week.
IV. Hormonal pills are taken on all days for as long as contraception has to be achieved.