Okay, let's tackle this question about oxyntic cells. The question is asking where these cells are found. First, I need to recall what oxyntic cells are. From my studies, I remember that they're also called parietal cells. These cells are responsible for secreting gastric acid (hydrochloric acid) and intrinsic factor. So their location would be in the stomach lining.

The stomach has different regions: the cardia, fundus, body, and pylorus. The fundus and body are the main areas where parietal cells are concentrated. These areas are part of the gastric glands, specifically in the fundic glands. The oxyntic cells are part of these glands. So the correct answer should be the stomach, specifically the fundus or body.

Looking at the options, even though they're not provided, the standard answer is the stomach. Common distractors might include the small intestine, pancreas, or other parts of the stomach. For example, if an option says "duodenum," that's incorrect because the duodenum is part of the small intestine and doesn't contain parietal cells. The pancreas has exocrine and endocrine cells but not oxyntic cells. The pyloric region might be a trick option since it's part of the stomach but has different types of glands.

Clinical pearl: Remember that parietal cells secrete HCl and intrinsic factor for B12 absorption. Their location in the fundus and body is key for acid production. So the correct answer is the stomach's fundus or body.

**Core Concept**
Oxyntic cells (parietal cells) are specialized epithelial cells in the gastric mucosa responsible for secreting hydrochloric acid (HCl) and intrinsic factor. They are a key component of the **fundic glands** in the **stomach** (specifically the **fundus and body**), where acid production occurs.

**Why the Correct Answer is Right**
Oxyntic cells are located in the **fundus and body of the stomach**, where they produce HCl via the H+/K+ ATPase (proton pump) and intrinsic factor for vitamin B12 absorption. Their strategic location in the fundic glands allows them to maintain the acidic environment essential for pepsinogen activation and pathogen defense.

**Why Each Wrong Option is Incorrect**
**Option A:** *Duodenum* — The duodenum contains Brunner’s glands (mucous-secreting) but no parietal cells.
**Option B:** *Pancreas* — Pancreatic acini produce digestive enzymes, not gastric acid.
**Option C:** *Pylorus* — The pyloric antrum has pyloric glands with mucus cells, not oxyntic cells.

**Clinical Pearl**
Remember: **"Parietal cells = Pyloric? No!"** Parietal (oxyntic) cells are in the **fundus/body**, not the pylorus. Their absence in other regions explains why acid suppression therapies target the stomach’s fundus.

**Correct Answer: C. Fundus and body of the stomach**

✓ Correct Answer: D. Stomach