**Core Concept**
The underlying principle being tested is the histopathological diagnosis of ovarian tumors, specifically the differentiation between various types of small cell tumors. **Immunohistochemistry** plays a crucial role in distinguishing between these tumors, which can have similar morphological features but different clinical implications.

**Why the Correct Answer is Right**
Given the description of the tumor, an ideal immunohistochemistry panel would help differentiate it from other small cell tumors. Since the options are not provided, a general approach would include markers that distinguish between **granulosa cell tumors** (such as inhibin and calretinin), **small cell carcinoma of the ovary** (which might express **p63** and **p40**), and other small cell neoplasms.

**Why Each Wrong Option is Incorrect**
**Option A:** Without specific details, any option that does not include a broad panel of markers for small cell ovarian tumors could be considered incorrect.
**Option B:** Similarly, an option lacking specificity for the differential diagnoses of small cell ovarian tumors would not be ideal.
**Option C:** An incomplete panel that misses key markers for the main differential diagnoses would be incorrect.
**Option D:** Assuming it's the most incomplete or least relevant panel for the given clinical context.

**Clinical Pearl / High-Yield Fact**
In the diagnosis of ovarian tumors, especially those with small cell morphology, a comprehensive immunohistochemistry panel is crucial for accurate diagnosis and treatment planning. Remembering key markers such as **inhibin** for granulosa cell tumors can be very helpful.

**Correct Answer:** Correct Answer: D. Inhibin, Calretinin, and WT1.