Which of the following is not a copper - releasing IUD ?

LNG-20.

The correct answer is Option (4) – LNG-20.

Among the options provided, "LNG-20" is not a copper-releasing IUD.

Cu-T, Cu-7, and Multiload 375 are examples of intrauterine devices (IUDs) designed to release copper. They are types of copper-containing IUDs used for contraception. These devices release Cu ions that suppress sperm motility and the fertilising capacity of sperms.

On the other hand, "LNG-20" is not a copper-releasing IUD. LNG-20 is a hormone releasing IUDs. LNG-20 does not contain copper and relies on hormonal mechanisms for contraception.The hormone releasing IUDs, in addition make the uterus unsuitable for implantation and the cervix hostile to the sperms.