It is known that exposure to carbon monoxide is harmful to animals because

Options

A. it reduces `CO_(2)` transport
B. it reduces `O_(2)` transport
C. it increases `CO_(2)` transport
D. it increases `O_(2)` transport.

Explanation

### Step-by-Step Solution:

1. **Understanding Carbon Monoxide (CO)**: Carbon monoxide is a colorless, odorless gas that can be harmful to living organisms, particularly animals and humans.

2. **Role of Hemoglobin**: Hemoglobin is a protein found in red blood cells that is responsible for transporting oxygen from the lungs to the rest of the body. Each hemoglobin molecule can bind up to four oxygen molecules.

3. **Binding Affinity**: Carbon monoxide has a much higher binding affinity for hemoglobin than oxygen does. This means that when both gases are present, carbon monoxide will preferentially bind to hemoglobin over oxygen.

4. **Consequences of CO Binding**: When carbon monoxide binds to hemoglobin, it occupies the binding sites that would normally be available for oxygen. This prevents oxygen from binding to hemoglobin effectively.

5. **Reduction in Oxygen Transport**: As a result of carbon monoxide binding to hemoglobin, the amount of oxygen that can be transported in the bloodstream is significantly reduced. This leads to a lack of oxygen being delivered to tissues and organs, which can be harmful or even fatal.

6. **Conclusion**: Therefore, exposure to carbon monoxide is harmful to animals primarily because it reduces the oxygen transport in the body.

### Final Answer:
Exposure to carbon monoxide is harmful to animals because it reduces the oxygen transport.

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