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

What is the purpose of contraceptive pills?
$I$. They inhibit ovulation and implantation
$II$. They alter the quality of cervical mucous to prevent or retard the entry of sperms
$III$. They prevent the ejaculated semen from entering the female vagina
$IV$. They inhibit spermatogenesis

The technique used to block the passage of sperm in males is . . . . . . .

Select the incorrect statement about contraceptives.

Which of the following is a second-generation (copper-releasing) $IUD$?

The action of a vaginal diaphragm is