**Core Concept**
Tonsillectomy is a surgical procedure to remove the tonsils, often performed to treat recurrent tonsillitis or sleep disorders. However, there are certain conditions where tonsillectomy is contraindicated due to increased risk of complications.

**Why the Correct Answer is Right**
The correct answer is related to a condition that affects the patient's overall health and increases the risk of post-operative bleeding or other complications. Tonsillectomy is contraindicated in patients with haemophilia, a genetic disorder characterized by a deficiency in clotting factor VIII or IX. This deficiency impairs the body's ability to form blood clots, making it difficult to stop bleeding after surgery.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not relevant to the contraindications of tonsillectomy. While certain medical conditions may increase the risk of complications, this option does not directly relate to the surgical procedure.
* **Option B:** This option is incorrect because it is not a contraindication for tonsillectomy. In fact, patients with certain types of bleeding disorders may require special precautions during surgery, but it is not an absolute contraindication.
* **Option C:** This option is not a contraindication for tonsillectomy. While patients with certain medical conditions may require special consideration before undergoing surgery, this option does not directly relate to the contraindications of tonsillectomy.

**Clinical Pearl / High-Yield Fact**
Haemophilia is a genetic disorder that affects the body's ability to form blood clots, making it difficult to stop bleeding after surgery. Patients with haemophilia require careful preoperative evaluation and may require special precautions during surgery to minimize the risk of complications.

**Correct Answer:** D. Haemophilia.