Haemoglobin is made up of two $\alpha$ chains and two $\beta$ chains. About $5\%$ of all humans have a change in one amino acid in the $\beta$ chain, which alters the structure and stability of haemoglobin. Which levels of protein structure could be affected in the haemoglobin of these humans?
- Aprimary only
- Bprimary and quaternary only
- Cprimary, secondary, tertiary and quaternary
- Dsecondary, tertiary and quaternary only