Which one is not a barrier method for birth control?

Intra Uterine Devices (IUDs)

The correct answer is Option (4)- Intra Uterine Devices (IUDs)

Diaphragms, cervical caps and vaults are barriers made of rubber that are inserted into the female reproductive tract to cover the cervix during coitus. They prevent conception by blocking the entry of sperms through the cervix. They are reusable.

An intrauterine device (IUD) is a form of birth control that a healthcare provider inserts into your uterus. Intra Uterine Devices are presently available as the non-medicated IUDs (e.g., Lippes loop), copper releasing IUDs (CuT, Cu7, Multiload 375) and the hormone releasing IUDs (Progestasert, LNG-20) . IUDs increase phagocytosis of sperms within the uterus and the Cu ions released suppress sperm motility and the fertilising capacity of sperms.