Lactational amenorrhoea is a natural way of birth spacing. It is due to the high level of

Among the following methods,which one has the highest failure rate?

Most of the contraceptive pills contain

Find out the correct choice for $Cu$-based $IUDs$.
$I$. Increases phagocytosis of sperms.
$II$. Releases $Cu^{2+}$ ions that suppress the sperm motility and fertilizing capacity of sperms.
$III$. Make the uterus unsuitable for implantation.

In the rhythm method of birth control,the couple refrains from intercourse:

Which of the following is an ideal contraceptive for females who want to delay pregnancy and space out children?