Pepsinogen is secreted by
(a) chief cell
(b) oxyntic cell
(c) mast cell
(d) parietal cell

Options

A. chief cell
B. oxyntic cell
C. mast cell
D. parietal cell

Explanation

To solve the question "Pepsinogen is secreted by," we will analyze each option provided:

1. **Understanding Pepsinogen**:
- Pepsinogen is an inactive precursor of the enzyme pepsin, which is involved in protein digestion. It is secreted in the stomach and is activated by hydrochloric acid (HCl).

2. **Analyzing the Options**:
- **(a) Chief cell**: These cells, also known as gastric chief cells or zymogenic cells, are responsible for the secretion of pepsinogen in the stomach.
- **(b) Oxyntic cell**: These are also known as parietal cells, which secrete hydrochloric acid (HCl) but do not secrete pepsinogen.
- **(c) Mast cell**: These cells are part of the immune system and are not involved in the secretion of digestive enzymes.
- **(d) Parietal cell**: As mentioned, these cells secrete HCl but not pepsinogen.

3. **Conclusion**:
- The correct answer is **(a) Chief cell**, as they are the cells that secrete pepsinogen in the stomach.

### Final Answer:
Pepsinogen is secreted by **(a) chief cell**.