**Core Concept**
The underlying principle being tested is the histopathological correlation of **Helicobacter pylori (H. pylori)** infection in the context of duodenal ulcers. **H. pylori** is a bacterium that can infect the stomach and duodenum, leading to inflammation and ulceration.

**Why the Correct Answer is Right**
The correct answer is related to the presence of **H. pylori** and its effects on the duodenal mucosa. **H. pylori** infection is associated with chronic active gastritis and duodenitis, characterized by **neutrophilic infiltration** and **mucosal inflammation**.

**Why Each Wrong Option is Incorrect**
**Option A:** This choice is incorrect because it does not directly relate to the typical histological findings in **H. pylori** infection.
**Option B:** Similarly, this option does not accurately describe the characteristic histopathological features of **H. pylori**-related duodenal ulcers.
**Option D:** This choice is also incorrect as it does not correspond to the expected histological findings in this context.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that **H. pylori** infection is a major cause of duodenal ulcers, and its diagnosis can be confirmed by endoscopic biopsy showing **active chronic gastritis** and **H. pylori** organisms.

**Correct Answer:** D. Active chronic gastritis.