$Cu$ ions released from copper-releasing intrauterine devices $(IUDs)$:

How do Intrauterine Devices $(IUDs)$ function as a method of birth control?

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

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.

One of the legal methods of birth control is

Which of the following contraceptives could be effective in avoiding pregnancy if used within $72$ hours after casual unprotected intercourse?