Which of the following factors help in the binding of oxygen with haemoglobin ?

Options

A. Partial pressure of carbon dioxide
B. Hydrogen ion concentration
C. Partial pressure of oxygen
D. All of the above

Answer

To determine which factors help in the binding of oxygen with hemoglobin, we need to analyze each option provided in the question.

### Step-by-Step Solution:

1. **Understanding Hemoglobin**: Hemoglobin is a red pigment found in red blood cells (RBCs) that binds to oxygen. Each hemoglobin molecule can bind up to four oxygen molecules.

2. **Analyzing the Options**:
- **Option A: Partial pressure of CO2**: An increase in the partial pressure of carbon dioxide (PCO2) can lead to a decrease in the affinity of hemoglobin for oxygen, promoting oxygen release rather than binding. Therefore, while it affects oxygen release, it does not directly help in binding.

- **Option B: Hydrogen ion concentration**: An increase in hydrogen ion concentration (lower pH) can also decrease the affinity of hemoglobin for oxygen, leading to the release of oxygen. This means that higher hydrogen ion concentration does not help in binding oxygen.

- **Option C: Partial pressure of oxygen**: The partial pressure of oxygen (PO2) is a critical factor for oxygen binding. Higher PO2 levels favor the binding of oxygen to hemoglobin, making this a positive factor for binding.

3. **Conclusion**: The only factor that directly helps in the binding of oxygen with hemoglobin is the partial pressure of oxygen. The other factors (PCO2 and hydrogen ion concentration) actually promote the release of oxygen from hemoglobin.

4. **Final Answer**: The correct answer is **C. Partial pressure of oxygen**.