**Core Concept**
The question is testing the student's knowledge of different types of Intrauterine Devices (IUDs) used for contraception, specifically their composition. Copper-containing IUDs are a common type of non-hormonal contraception.

**Why the Correct Answer is Right**
LNG-20, also known as Mirena, is a type of hormonal IUD that releases levonorgestrel, a synthetic progestin. It does not contain copper, unlike other IUDs mentioned in the options. This is because LNG-20 works by releasing a steady dose of levonorgestrel, which thickens cervical mucus, preventing sperm from reaching the egg, and also thinning the uterine lining, making it less receptive to implantation. In contrast, copper-containing IUDs work by releasing ions that are toxic to sperm.

**Why Each Wrong Option is Incorrect**
**Option A:** CuT-200 is a copper-containing IUD, specifically a type of T-shaped intrauterine device with a copper core. It releases ions that are toxic to sperm, making it an effective form of non-hormonal contraception.
**Option B:** Nova-T is another copper-containing IUD, similar to CuT-200. It is a T-shaped device with a copper core and works by releasing ions that are toxic to sperm.
**Option C:** Multiload-250 is a copper-containing IUD, specifically a type of frame IUD with a copper core. It is designed to be more effective than other copper IUDs and works by releasing ions that are toxic to sperm.

**Clinical Pearl / High-Yield Fact**
It's essential to note that while copper-containing IUDs are effective forms of non-hormonal contraception, they may not be suitable for everyone, particularly those with a history of pelvic inflammatory disease or those who are sensitive to copper. Additionally, copper IUDs may increase the risk of menstrual cramps and heavy bleeding in some women.

**✓ Correct Answer: D. LNG-20**