The affinity of haemoglobin for carbon monoxide is more than its affinity for oxygen.

Explanation

### Step-by-Step Solution:

1. **Understanding Hemoglobin**: Hemoglobin is a protein found in red blood cells (RBCs) that is responsible for transporting oxygen from the lungs to the rest of the body. It contains iron, which allows it to bind to oxygen.

2. **Affinity Definition**: The term "affinity" refers to the strength of the binding between hemoglobin and the gases it carries. A higher affinity means that hemoglobin binds more tightly to the gas.

3. **Comparing Affinities**: It is known that hemoglobin has a higher affinity for carbon monoxide (CO) than for oxygen (O2). This means that when both gases are present, hemoglobin will preferentially bind to carbon monoxide over oxygen.

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