Which of the following is not a barrier method of birth control.

The correct answer is Option (3) → Sterilization

Barrier methods stop the ovum and sperms from meeting physically.

Option (1) Vaults — A barrier method.

Option (2) Diaphragms — A barrier method.

Option (3) Sterilization — Not a barrier method. It is a surgical method: vasectomy in males and tubectomy in females block the transport of gametes permanently.

Option (4) Cervical caps — A barrier method.

NCERT Extract:
Population Stabilisation and Birth Control – “… In barrier methods, ovum and sperms are prevented from physically meeting with the help of barriers. Such methods are available for both males and females. Condoms (Figure 3.1 a, b) are barriers made of thin rubber/ latex sheath that are used to cover the penis in the male or vagina and cervix in the female, just before coitus so that the ejaculated semen would not enter into the female reproductive tract. This can prevent conception. ‘Nirodh’ is a popular brand of condom for the male. Use of condoms has increased in recent years due to its additional benefit of protecting the user from contracting STIs and AIDS. Both the male and the female condoms are disposable, can be self-inserted and thereby gives privacy to the user. Diaphragms, cervical caps and vaults are also barriers made of rubber that are inserted into the female reproductive tract to cover the cervix during coitus.”
Population Stabilisation and Birth Control – “… Surgical intervention blocks gamete transport and thereby prevent conception. Sterilisation procedure in the male is called ‘vasectomy’ and that in the female, ‘tubectomy’.”