In Sickle-Cell Disease, as a Result of a Single Amino

In sickle-cell disease, as a result of a single amino acid change, the mutant haemoglobin tetramers associate with each other and assemble into large fibres. Based on this information alone, we can conclude that sickle-cell haemoglobin exhibits ________.

A) only altered primary structure
B) only altered tertiary structure
C) only altered quaternary structure
D) altered primary structure and altered quaternary structure; the secondary and tertiary structures may or may not be altered