**Core Concept**
X-linked agammaglobulinemia (XLA) is a rare genetic disorder characterized by the absence of B cells and consequently, low levels of all classes of immunoglobulins. This condition results from mutations in the BTK gene, which encodes the tyrosine kinase enzyme responsible for B cell development and activation.

**Why the Correct Answer is Right**
The correct answer is related to the clinical presentation of XLA, which typically includes recurrent infections, particularly of the respiratory, gastrointestinal, and genitourinary tracts. The hallmark feature of XLA is the absence of B cells, leading to low levels of all classes of immunoglobulins. This results in impaired antibody production, making patients susceptible to infections.

**Why Each Wrong Option is Incorrect**
**Option A:** Elevated serum immunoglobulin M (IgM) levels are not a characteristic feature of XLA, as the condition is associated with low levels of all classes of immunoglobulins.
**Option B:** Recurrent infections are a feature of XLA, but they are not limited to the skin. Infections can occur in any part of the body, including the respiratory, gastrointestinal, and genitourinary tracts.
**Option C:** The presence of neutropenia is not a characteristic feature of XLA, as the condition primarily affects B cells and immunoglobulin production.

**Clinical Pearl / High-Yield Fact**
X-linked agammaglobulinemia should be considered in the differential diagnosis of recurrent infections in males, particularly those with a family history of the condition.

**Correct Answer:** C. Recurrent infections in males.