Drugs can be classified on the basis of

Options

A. Pharmocological effect
B. Drug action
C. Chemical structure
D. All of these

Answer

### Step-by-Step Solution:

1. **Understanding Drug Classification**: Drugs can be classified based on various criteria. The main categories include pharmacological effect, drug action, and chemical structure.

2. **Pharmacological Effect**: This classification refers to the role or function of the drug in the body. For example, drugs can be classified as:
- Antacids (used to neutralize stomach acid)
- Antimicrobials (used to kill or inhibit the growth of microorganisms)
This means that drugs can be grouped based on their therapeutic effects.

3. **Drug Action**: This classification focuses on where the drug acts within the body. It looks at the specific sites or systems that the drug targets. For example:
- Drugs acting on the central nervous system (CNS)
- Drugs acting on the cardiovascular system
This classification helps in understanding the mechanism of action of the drug.

4. **Chemical Structure**: Drugs can also be classified based on their chemical composition and structure. For example:
- Drugs that contain sulfur may be prefixed with 'S' in their names.
- This classification is important for understanding the chemical properties and potential interactions of the drugs.

5. **Conclusion**: Since drugs can be classified based on pharmacological effect, drug action, and chemical structure, the correct answer to the question is "All of this."

### Final Answer:
Drugs can be classified on the basis of pharmacological effect, drug action, and chemical structure. Therefore, the correct option is "All of this."

---