## **Core Concept**
The question pertains to the duration of effectiveness of various Intrauterine Contraceptive Devices (IUCDs). IUCDs are a type of long-acting reversible contraception, and their lifespan varies depending on the type and model.

## **Why the Correct Answer is Right**
The IUCD with the shortest lifespan among the commonly used ones is the **Copper T 200**. It releases copper ions and is effective for about 4 years. The lifespan of IUCDs can vary:
- Copper T 380A (ParaGard) is effective for 10 years.
- Levonorgestrel-releasing intrauterine systems (Mirena, Kyleena, Skyla) have varying durations of effectiveness, typically 5-7 years, depending on the model.

## **Why Each Wrong Option is Incorrect**
- **Option A:** If an IUCD has a longer lifespan than 4 years, it would not be the correct answer. For example, Copper T 380A has a longer lifespan.
- **Option B:** Similarly, if another IUCD has a lifespan longer than 4 years or comparable but not the shortest, it wouldn't be correct.
- **Option D:** If an IUCD has a longer or even comparable lifespan, such as the Levonorgestrel-releasing systems, it wouldn't be the one with the shortest lifespan.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that while IUCDs offer long-term contraception, their effectiveness and duration can vary. The Copper T 200, with its 4-year lifespan, is less commonly referenced today due to the availability of IUCDs with longer durations of action and lower side effect profiles.

## **Correct Answer:** B. Copper T 200.