**Core Concept**
The underlying principle being tested is the histopathological correlation of Helicobacter pylori infection in the context of duodenal ulcers. **Helicobacter pylori** is a bacterium that can cause stomach infections and is strongly linked to the development of duodenal ulcers.

**Why the Correct Answer is Right**
Given the association between **H. pylori** and duodenal ulcers, an endoscopic biopsy from such a case would most likely reveal evidence of the infection, such as the presence of **H. pylori** bacteria, **inflammation**, and **gastric metaplasia** in the duodenal mucosa. The bacteria induce an inflammatory response that can lead to mucosal damage and ulcer formation.

**Why Each Wrong Option is Incorrect**
**Option A:** This choice is incorrect because while **neutrophilic infiltration** can be seen in the context of **H. pylori** infection, it is not the most specific finding.
**Option B:** This option is wrong as **eosinophilic infiltration** is more commonly associated with allergic reactions or parasitic infections, not typically with **H. pylori**.
**Option D:** This choice is incorrect as **lymphocytic infiltration** can be seen in various conditions, including viral infections and autoimmune disorders, and is not specific to **H. pylori**.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that **H. pylori** infection is a major cause of duodenal ulcers and that eradication of the bacteria can lead to healing of the ulcers.

**Correct Answer:** C. Active chronic gastritis with presence of H. pylori.