The graph illustrates the effect of varying oxygen concentration on the percentage oxygen saturation of human haemoglobin and cat haemoglobin in normal physiological conditions. The partial pressure of carbon dioxide remained fixed at $5.0\,\text{kPa}$ and the temperature remained fixed at $37^\circ\text{C}$. Which conclusion is supported by the graph?
- AThe affinity of cat haemoglobin for oxygen is greater than the affinity of human haemoglobin for oxygen.
- BAt high partial pressures of oxygen, cat haemoglobin picks up oxygen more easily than human haemoglobin picks up oxygen.
- CAt low partial pressures of oxygen, oxygen is released more easily from cat haemoglobin than from human haemoglobin.
- DThe shift in the oxygen dissociation curve caused by the Bohr effect is larger for cat haemoglobin than for human haemoglobin.