**Core Concept**
Haemolytic anemia is a condition characterized by the premature destruction of red blood cells (RBCs), leading to anemia. This can be caused by various factors, including genetic disorders, infections, and autoimmune diseases.

**Why the Correct Answer is Right**
The correct answer, **Paroxysmal Nocturnal Hemoglobinuria (PNH)**, is a rare acquired disorder that affects the RBCs, leading to their premature destruction. PNH is caused by a mutation in the PIGA gene, which codes for an enzyme involved in the synthesis of glycosylphosphatidylinositol (GPI), an important anchor for proteins on the RBC surface. This mutation leads to a deficiency of GPI-anchored proteins, including CD55 and CD59, which normally protect RBCs from complement-mediated lysis. As a result, PNH RBCs are more susceptible to destruction by the complement system, leading to haemolytic anemia.

**Why Each Wrong Option is Incorrect**
* **Option A:** Sickle Cell Anemia is a genetic disorder caused by a mutation in the HBB gene, leading to abnormal hemoglobin production and RBC deformation. While it can cause anemia, it is not typically characterized by haemolytic anemia.
* **Option B:** G6PD Deficiency is a genetic disorder affecting the enzyme glucose-6-phosphate dehydrogenase, which protects RBCs from oxidative stress. While it can cause haemolytic anemia, it is not the correct answer in this context.
* **Option C:** Autoimmune Hemolytic Anemia (AIHA) is an autoimmune disorder where the immune system produces antibodies against RBCs, leading to their destruction. While AIHA is a type of haemolytic anemia, it is not the correct answer in this context.

**Clinical Pearl / High-Yield Fact**
PNH is a rare but serious condition that can be challenging to diagnose. A key diagnostic feature is the presence of hemoglobinuria (hemoglobin in the urine) after physical activity or stress.

**Correct Answer: C. Autoimmune Hemolytic Anemia (AIHA)**