## **Core Concept**
Intrinsic factor is a glycoprotein produced in the stomach that plays a crucial role in the absorption of vitamin B12. It binds to vitamin B12 from food and facilitates its absorption in the ileum. The production of intrinsic factor is essential for preventing vitamin B12 deficiency.

## **Why the Correct Answer is Right**
The correct answer, **parietal cells**, are responsible for secreting intrinsic factor. Parietal cells, also known as oxyntic cells, are found in the gastric glands of the stomach lining. They secrete hydrochloric acid and intrinsic factor. The intrinsic factor produced by parietal cells is critical for the subsequent binding and absorption of vitamin B12 in the terminal ileum.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Chief cells primarily secrete pepsinogen, which is converted to pepsin to help digest proteins in the stomach. They do not produce intrinsic factor.
- **Option B:** Mucous cells produce mucus to protect the stomach lining from acid and enzymes. They are not involved in the production of intrinsic factor.
- **Option C:** This option might seem plausible because enterochromaffin-like cells (ECL cells) are involved in the regulation of acid production but are not directly responsible for intrinsic factor secretion.

## **Clinical Pearl / High-Yield Fact**
A key clinical correlation is that patients with **pernicious anemia**, an autoimmune condition leading to the destruction of parietal cells, have a deficiency in intrinsic factor production. This results in vitamin B12 deficiency, which can cause neurological problems and anemia if not treated.

## **Correct Answer:** . Parietal cells.