Out of the following options,identify which one is $NOT$ a natural method of contraception.

The chemical method of contraception includes:

When can emergency contraceptives be used?

Describe the usage of Nirodh/condom as a contraceptive method of family planning.

What is the full form of $IUCDs$?

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