Which one of the following is used as Antihistamine?

Options

A. Omeprazole
B. Chloranphenicol
C. Diphenhydramine
D. Norethindrone

Explanation

### Step-by-Step Solution:

1. **Understanding Antihistamines**:
- Antihistamines are drugs that block the action of histamine, a substance in the body that causes allergic symptoms. They are commonly used to relieve symptoms of allergies, hay fever, and colds.

2. **Analyzing the Options**:
- We have four options to consider: Omeprazole, Chloramphenicol, Diphenylhydramine, and Northenrol.

3. **Identifying Each Option**:
- **Omeprazole**: This is a proton pump inhibitor used to treat gastroesophageal reflux disease (GERD) and other stomach-related issues. It is not an antihistamine.
- **Chloramphenicol**: This is an antibiotic used to treat bacterial infections. It does not have antihistamine properties.
- **Diphenylhydramine**: This is a well-known antihistamine used to relieve symptoms of allergy, hay fever, and the common cold. It is effective in blocking histamine.
- **Northenrol**: This is not widely recognized as a standard medication and does not have established antihistamine properties.

4. **Conclusion**:
- Among the options provided, **Diphenylhydramine** is the drug that is used as an antihistamine.

### Final Answer:
**Diphenylhydramine** is used as an antihistamine.

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