$A$ method of birth control is:

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

The sterilization procedure in human female is:

$Norplant$ is a new form of birth control,and it:

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

Which of the following conditions can help in avoiding fertilization?