Sickle cell anemia is :

The correct option is D Caused by a change in a single base pair of DNA
Sickle cell anemia results in an abnormality in the oxygen-carrying protein hemoglobin found in red blood cells.
This leads to a rigid, sickle-like shape of the enucleated RBC's.
It is an autosomal recessive disorder which is caused by a change in a single base pair of hemoglobin gene resulting in glutamic acid (E/Glu) being substituted by valine (V/Val) of the beta globin chain of hemoglobin.