**Agammaglobulinemia Presentation**

**Core Concept**
Agammaglobulinemia is a rare genetic disorder characterized by the inability of the body to produce antibodies due to a defect in B-cell development or function. This leads to impaired humoral immunity and increased susceptibility to infections.

**Why the Correct Answer is Right**
The correct answer is linked to the pathophysiology of agammaglobulinemia, where the absence of antibodies exposes the individual to infections, particularly those caused by encapsulated bacteria such as *Streptococcus pneumoniae*. The clinical presentation of recurrent infections, particularly otitis media, sinusitis, and pneumonia, is a hallmark of this disorder.

**Why Each Wrong Option is Incorrect**
**Option A:** Allergic reactions are not a characteristic feature of agammaglobulinemia, as the defect lies in antibody production, not in the immune response to allergens.

**Option B:** Autoimmune disorders are not directly related to agammaglobulinemia, as the defect lies in the production of antibodies, not in the regulation of the immune response.

**Option C:** While agammaglobulinemia can increase the risk of infections, it is not typically associated with an increased risk of malignancy.

**Clinical Pearl / High-Yield Fact**
Agammaglobulinemia is often associated with X-linked inheritance, and males are more commonly affected than females.

**Correct Answer: C. Infections, particularly those caused by encapsulated bacteria.**