Which of the following results in high content of carboxyhaemoglobin in blood ?

Options

A. Smoking and alcohol
B. Alcohol
C. Cannabinoids
D. Smoking but not alcohol

Answer

### Step-by-Step Solution:

1. **Understanding Carboxyhemoglobin**:
- Carboxyhemoglobin is a compound formed when carbon monoxide (CO) binds to hemoglobin in the blood. This reduces the blood's ability to carry oxygen.

2. **Identifying Sources of Carbon Monoxide**:
- Carbon monoxide is produced from incomplete combustion of carbon-containing fuels. Common sources include cigarette smoke, vehicle emissions, and industrial processes.

3. **Analyzing the Options**:
- **Option A: Smoking and Alcohol**: While smoking introduces carbon monoxide into the bloodstream, alcohol does not produce carbon monoxide.
- **Option B: Alcohol**: Alcohol does not contain carbon monoxide and therefore does not lead to increased carboxyhemoglobin levels.
- **Option C: Cannabinoids**: Cannabinoids do not produce carbon monoxide and thus do not affect carboxyhemoglobin levels.
- **Option D: Smoking but not Alcohol**: This option correctly identifies that smoking introduces carbon monoxide into the blood.

4. **Conclusion**:
- The correct answer is **Smoking but not Alcohol**. Smoking leads to a high content of carboxyhemoglobin in the blood due to the presence of carbon monoxide in cigarette smoke.