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

The mechanical measures of population control include:

What is true about 'Saheli'?
$I$. Developed at $CDRI$,Lucknow
$II$. Contains a steroidal preparation
$III$. 'Once-a-week' pill
$IV$. Many side effects
$V$. High contraceptive value
$VI$. Very few side effects
$VII$. Low contraceptive value

Find out the correct statement.
$I$. Pills prevent ovulation during use as a contraception technique.
$II$. Copper-$T$ prevents implantation.
$III$. Vasectomy produces semen containing no sperm.

Tubectomy is a method of sterilization in which

The use of . . . . . . is very effective as an emergency contraceptive.