Sickle-Cell Disease Is an Inherited Disease Caused by an Alteration

Sickle-cell disease is an inherited disease caused by an alteration of a single amino acid in a protein. Specifically,

A) the sixth amino acid, glutamic acid, is replaced by valine.
B) the sixth amino acid, glutamic acid, is replaced by lysine.
C) the charge of the protein is changed, which causes the protein to change shape.
D) Both a and c
E) Both b and c