## **Core Concept**
Hemophilia is a genetic disorder characterized by the deficiency of a specific clotting factor in the blood, leading to impaired coagulation. The inheritance pattern of hemophilia is linked to the X chromosome. This condition primarily affects males, as they have only one X chromosome.

## **Why the Correct Answer is Right**
Hemophilia A and B, the most common types, are caused by deficiencies in clotting factor VIII and IX, respectively. Both of these genes are located on the X chromosome. Males have one X and one Y chromosome (XY), while females have two X chromosomes (XX). Because males have only one X chromosome, a single mutation in the gene for factor VIII or IX is enough to cause the condition. Females, on the other hand, would need both X chromosomes to have the mutation to express the condition, making it much less common in females. However, females can be carriers, having one normal and one mutated gene, and can pass the mutated gene to their offspring. This pattern is characteristic of **X-linked recessive inheritance**.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because an autosomal dominant pattern would mean a single copy of the mutated gene is enough to cause the condition, and it would affect males and females equally, which is not the case with hemophilia.
- **Option B:** This option suggests an autosomal recessive pattern, which would require two copies of the mutated gene (one from each parent) to express the condition. While this could explain the lower incidence in females, it doesn't account for the preferential affectation of males.
- **Option D:** This option implies a Y-linked inheritance, which would mean the condition is passed from father to son. However, hemophilia is not exclusively passed from fathers to sons, and daughters can be carriers.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that while hemophilia primarily affects males, females can be carriers. If a female is a carrier, there's a 50% chance she'll pass the affected X chromosome to each son (who would be affected) and to each daughter (who would typically be a carrier like her mother). This inheritance pattern is a classic example of X-linked recessive disorders.

**Correct Answer: C. X-linked Recessive**