Antazoline is used as the following .

Options

A. Antihistamine
B. Food preservative
C. Analgesic
D. Anti-cancer drug

Answer

### Step-by-Step Solution:

1. **Understanding Antazoline**:
- Antazoline is a chemical compound that has a specific structure, which includes a benzene ring and a nitrogen group.

2. **Identifying the Uses of Antazoline**:
- The question asks about the uses of Antazoline. We need to evaluate the options provided: antihistamine, food preservative, analgesic, and anti-cancer drug.

3. **Defining Antihistamine**:
- An antihistamine is a type of medication that counteracts the effects of histamine in the body. Histamine is a compound that is involved in allergic reactions.

4. **Analyzing the Effects of Histamine**:
- Histamine release in the body can lead to various allergic symptoms, such as itching, swelling, and redness. Antihistamines are used to alleviate these symptoms.

5. **Evaluating Other Options**:
- **Food Preservative**: This is used to prevent food spoilage and is not related to the action of Antazoline.
- **Analgesic**: This refers to pain-relieving medications, which do not match the properties of Antazoline.
- **Anti-cancer Drug**: This type of drug is specifically designed to treat cancer, which is not the function of Antazoline.

6. **Conclusion**:
- Based on the analysis, Antazoline is primarily used as an antihistamine to treat allergies, particularly eye allergies. Therefore, the correct answer is **antihistamine**.