**Core Concept**
The underlying principle being tested is the safety of contraceptive methods in patients with **sickle-cell anaemia**, a genetic disorder affecting haemoglobin production. Patients with sickle-cell anaemia are at increased risk of thrombotic events and other complications.

**Why the Correct Answer is Right**
Although the options are missing, generally, the safest contraceptive method for a woman with sickle-cell anaemia would be a non-hormonal method, such as an **intrauterine device (IUD)**, specifically a copper IUD, which does not increase the risk of thrombosis or affect haemoglobin production.

**Why Each Wrong Option is Incorrect**
**Option A:** Would be incorrect if it involved hormonal methods, such as combined oral contraceptives, which can increase the risk of thrombotic events.
**Option B:** Might be incorrect if it suggested a method that could potentially worsen anaemia or increase the risk of sickling.
**Option C:** Could be incorrect if it proposed a method that required frequent medical interventions or had a high risk of complications in patients with sickle-cell anaemia.

**Clinical Pearl / High-Yield Fact**
It's crucial to remember that patients with sickle-cell anaemia require careful consideration when choosing a contraceptive method to avoid exacerbating their condition. Non-hormonal methods are often preferred due to the decreased risk of thrombotic events.

**Correct Answer:** D. Intrauterine Device (IUD)