**Core Concept**
Hemophilia is a group of bleeding disorders characterized by the deficiency or dysfunction of clotting factors, leading to prolonged bleeding and bruising. The two main types of hemophilia are Hemophilia A (deficiency of factor VIII) and Hemophilia B (deficiency of factor IX). Understanding the pathophysiology of hemophilia is crucial for managing and treating these disorders.

**Why the Correct Answer is Right**
The correct answer will be related to a characteristic of hemophilia that is not true. Hemophilia is an X-linked recessive disorder, primarily affecting males. This is because the genes responsible for encoding factor VIII and factor IX are located on the X chromosome. Females can be carriers of the disease, but they are usually asymptomatic or have mild symptoms due to X-chromosome inactivation.

**Why Each Wrong Option is Incorrect**
**Option A:** Hemophilia is caused by a deficiency of factor X. This is incorrect because Hemophilia A is caused by a deficiency of factor VIII, while Hemophilia B is caused by a deficiency of factor IX. Factor X deficiency is a different bleeding disorder.

**Option B:** Hemophilia is an autosomal dominant disorder. This is incorrect because Hemophilia is an X-linked recessive disorder, primarily affecting males.

**Option C:** Hemophilia can be treated with desmopressin. This is incorrect because desmopressin is used to treat mild Hemophilia A, but it is not effective for Hemophilia B. Additionally, desmopressin is not used for severe Hemophilia A.

**Clinical Pearl / High-Yield Fact**
The severity of hemophilia is classified into three types: mild, moderate, and severe, based on the level of factor VIII or IX activity in the blood. Patients with mild hemophilia may never experience symptoms, while those with severe hemophilia may experience frequent and spontaneous bleeding.

**Correct Answer: B. Hemophilia is an autosomal dominant disorder.**