**Core Concept**
Menorrhagia refers to abnormally heavy or prolonged menstrual bleeding, which can be treated with various medical and surgical interventions. Intrauterine devices (IUDs) are a type of long-term contraception that can also be used to manage menorrhagia by inducing amenorrhea or reducing menstrual bleeding.

**Why the Correct Answer is Right**
The Mirena IUD is a levonorgestrel-releasing intrauterine system (LNG-IUS) that works by releasing a small amount of the progestin levonorgestrel, which thickens the cervical mucus, thinning the uterine lining, and reducing menstrual bleeding. This makes it an effective treatment option for patients with menorrhagia. The LNG-IUS also has a local effect on the endometrium, which helps to reduce bleeding and induce amenorrhea.

**Why Each Wrong Option is Incorrect**
**Option A:** The Copper T IUD is a non-hormonal device that works by releasing copper ions, which create a toxic environment for sperm, preventing fertilization. It does not have a direct effect on menstrual bleeding.
**Option B:** The Nova T IUD is a levonorgestrel-releasing IUD, but it is not specifically used for treating menorrhagia. It is primarily used as a contraceptive device.
**Option C:** The Progestasert IUD is a progesterone-releasing IUD, but it is not commonly used for treating menorrhagia. It is primarily used as a contraceptive device.

**Clinical Pearl / High-Yield Fact**
Remember that the LNG-IUS (Mirena) is not only effective for contraception but also for treating menorrhagia and improving quality of life for patients with heavy menstrual bleeding.

**Correct Answer:** C. Progestasert