Red blood cells are responsible for transporting oxygen in the blood. People with sickle cell anemia were born with a defective gene that results in sickle-shaped red blood cells. Individuals with the disease often suffer pain in their extremities due to the build-up of these cells causing blockages in the blood vessels. The shape of the blood cells also reduces the amount of oxygen transported in the blood.

The image below shows a side-by-side comparison of normal and sickle-shaped red blood cells.

Image courtesy of NIH.

Which of the following medical treatments would cause changes to the genetic material of the patient?
A.
replacing the blood in the body via transfusions
B.
replacing the malfunctioning gene with a healthy copy
C.
providing drugs to increase oxygen levels in the blood
D.
targeting and killing sickle cell