**Core Concept**
The question is testing the ability to identify a specific stain used for diagnosing a particular disease transmitted by fleas. This requires knowledge of the causative agent, its life cycle, and the diagnostic techniques employed.

**Why the Correct Answer is Right**
The symptoms described, such as fever and axillary lymphadenopathy, suggest the diagnosis of **Trench Fever**, caused by the bacterium **Bartonella quintana**. This bacterium is transmitted through the bite of an infected flea. To diagnose Bartonella quintana, a **Wright's stain** is used for smear preparation, which helps in identifying the characteristic "safety pin" appearance of the bacteria.

**Why Each Wrong Option is Incorrect**
**Option A:** Giemsa stain is used for diagnosing malaria, not Bartonella quintana.
**Option B:** Methenamine silver stain is used for diagnosing fungi, not Bartonella quintana.
**Option C:** Alcian blue stain is used for detecting mucin in tissues, not Bartonella quintana.

**Clinical Pearl / High-Yield Fact**
Wright's stain is a crucial tool in the diagnosis of various bacterial infections, including Bartonella quintana. It is essential to be familiar with the characteristic appearance of different bacteria under the microscope to make an accurate diagnosis.

**Correct Answer:** C. Wright's stain.