**Core Concept**
The IUCD (Intrauterine Contraceptive Device) is a type of long-acting reversible contraceptive that works by releasing hormones or releasing a physical barrier within the uterus to prevent fertilization. The device is made up of various materials, including metals, plastics, and other synthetic materials.

**Why the Correct Answer is Right**
The IUCD typically consists of a T-shaped frame with a copper or hormone-releasing component. The copper IUCD, also known as the copper T, works by releasing copper ions that are toxic to sperm, thereby preventing fertilization. The hormone-releasing IUCD, such as the Mirena, releases levonorgestrel, a synthetic progestin that thins the cervical mucus, preventing sperm from reaching the egg.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it is not specific to the materials used in IUCD manufacturing. While some IUCDs may be made from plastics, this is not the primary material composition.
* **Option B:** This option is incorrect because it is not accurate for the majority of IUCDs. While some IUCDs may have a copper component, not all IUCDs are made of copper.
* **Option C:** This option is incorrect because it is not a specific material used in IUCD manufacturing. IUCDs may be made from a variety of materials, but this option is too vague.

**Clinical Pearl / High-Yield Fact**
It is essential to note that IUCDs are a highly effective form of birth control, with a failure rate of less than 1%. However, they may not be suitable for all patients, particularly those with a history of pelvic inflammatory disease or those who are sensitive to copper or hormones.

**Correct Answer: D. Metal and plastic.**