Which of the following is not a natural method of contraception?

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

Match Column $-I$ with Column $-II$.

Column $-I$ (Method)	Column $-II$ (Mode of Action)
$A$. The pill	$I$. Prevents sperms reaching cervix
$B$. Condom	$II$. Prevents implantation
$C$. Vasectomy	$III$. Prevents ovulation
$D$. Copper $T$	$IV$. Semen contains no sperms

Lippe's loop is a type of contraceptive used as:

Saheli is developed by :

Diaphragms are contraceptive devices used by females. Choose the correct option from the statements given below:
$i$. They are introduced into the uterus
$ii$. They are placed to cover the cervical region
$iii$. They act as physical barriers for sperm entry
$iv$. They act as spermicidal agents