How do diaphragms,cervical caps,and vaults function as contraceptives?

What is the purpose of cutting the vas deferens?

Assertion: $HIV$ infection can be avoided by the use of condoms.
Reason: Condoms secrete anti-viral interferons.

Contraceptive pills are very effective with lesser side effects and are well accepted by females. They work by:

Give information about natural methods useful as contraceptives.

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