## **Core Concept**
The question tests knowledge of bleeding disorders and their manifestations. The symptoms described, such as bleeding from gums and a swollen knee, are indicative of a coagulopathy. Specifically, this presentation suggests a disorder affecting platelet count or function, or a coagulation factor deficiency.

## **Why the Correct Answer is Right**
The correct answer, **C. Hemophilia A**, is a genetic disorder caused by a deficiency in **Factor VIII**, a crucial protein for blood coagulation. Hemophilia A can lead to easy bruising, joint pain and swelling (due to bleeding into joints), and mucocutaneous bleeding (such as gum bleeding). The swollen knee is suggestive of a hemarthrosis, which is a common complication in patients with hemophilia. The disorder primarily affects males due to its X-linked recessive inheritance pattern.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because the condition described does not match the symptoms provided.
- **Option B:** This option does not align with the clinical presentation of bleeding gums and a swollen knee due to a different pathophysiological mechanism.
- **Option D:** This option is incorrect as it does not fit the clinical scenario of a bleeding disorder with joint involvement.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that **Hemophilia A** and **Hemophilia B** (deficiency of Factor IX) are characterized by their X-linked recessive inheritance and primarily affect males. A significant clinical clue is the presence of joint swelling (hemarthrosis) and mucocutaneous bleeding, which are hallmarks of these coagulopathies.

## **Correct Answer:** . **Hemophilia A**