**Step-by-Step Solution:**
1. **Understanding Paracetamol**: Paracetamol, also known as acetaminophen, is a commonly used medication. It is primarily known for its pain-relieving (analgesic) and fever-reducing (antipyretic) properties.
2. **Analyzing the Options**: The question provides four options regarding what paracetamol reduces:
- Option 1: Blood Pressure
- Option 2: Fever
- Option 3: Hypertension
- Option 4: Allergy
3. **Evaluating Each Option**:
- **Blood Pressure**: Paracetamol is not known to reduce blood pressure. It does not have any significant effect on blood pressure levels.
- **Fever**: Paracetamol is well-known for its ability to reduce fever. It acts on the hypothalamus in the brain to help lower body temperature when it is elevated.
- **Hypertension**: Similar to blood pressure, paracetamol does not have a direct effect on hypertension. It is not used to treat high blood pressure.
- **Allergy**: Paracetamol does not treat allergies. Antihistamines are typically used for allergic reactions.
4. **Conclusion**: Based on the analysis, the only option that paracetamol effectively reduces is fever. Therefore, the correct answer is **Option 2: Fever**.
