Which statement is correct about the way oxygen combines with haemoglobin?
- ACombining all four oxygen molecules with haemoglobin does not affect the shape of haemoglobin.
- BOne oxygen molecule can combine with each haem group of the haemoglobin molecule.
- CThe first oxygen molecule to combine with haemoglobin does not affect the shape of haemoglobin.
- DThe third oxygen molecule to combine with haemoglobin makes it more difficult for the fourth oxygen molecule to combine with haemoglobin.