Which of the following contraceptive methods has a very high failure rate?

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

Choose the correct option which can be used by females as injections or implants under the skin for contraception from the following:
$(i)$ Progestogens
(ii) Progestogen + estrogen combinations
(iii) Estrogen
(iv) Progestasert

Discuss the mode of action and advantages/disadvantages of hormonal contraceptives.

The diaphragm is a rubber dome-shaped structure that stops sperms from entering into:

One of the following is not a method of contraception. Which one?