## **Core Concept**
X-linked recessive inheritance refers to a pattern of inheritance where the responsible gene is located on the X chromosome. Conditions with this inheritance pattern typically affect males more frequently than females because males have only one X chromosome. If that X chromosome carries the mutation, they will express the condition since they do not have another X chromosome to compensate.

## **Why the Correct Answer is Right**
The correct answer, , is associated with X-linked recessive inheritance. This condition results from a deficiency of factor VIII, a crucial protein for blood clotting. The gene encoding factor VIII is located on the X chromosome. Males are more frequently affected because they have one X and one Y chromosome; if their single X chromosome has the mutation, they will develop the condition. Females would need both X chromosomes to have the mutation to express the condition, making it less common in females.

## **Why Each Wrong Option is Incorrect**
- **Option A:** is not exclusively X-linked recessive; it can have various inheritance patterns depending on the subtype.
- **Option B:** is typically inherited in an autosomal dominant pattern, not X-linked recessive.
- **Option C:** does not follow a straightforward X-linked recessive pattern; its inheritance can be more complex.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that X-linked recessive conditions, like , often present with severe symptoms in males, while females are usually carriers unless they are homozygous for the mutation, which is rare. A classic example in exams is that of hemophilia A and B, which are X-linked recessive disorders.

## **Correct Answer:** . Haemophilia A