Choose the correct answer among the alternatives given :
What is true for lactational amenorrhea?
(i) It means absence of menstruation.
(ii) Ovulation does not occur during the lactational period.
(iii) Chances of contraception are almost nil upto six months following parturition.
(iv) Side effects are almost nil
(v) Contraceptive efficiency reduces after the period of intense lactation.
(vi) It is a natural method of contraception.
(vii) It increases phagocytosis of sperms.