The Immune Disorder Adenosine Deaminase (ADA) Deficiency, Is the Result

The immune disorder adenosine deaminase (ADA) deficiency, is the result of a mutation in one gene. How could gene therapy be used to treat this disorder?

A) Red blood cells could be induced to produce the protein encoded by the mutated ADA gene.
B) Cells containing a corrected ADA gene could be injected into patients with ADA.
C) Synthetic blood cells could be swallowed by the patients.
D) Patients could be injected with a hybrid molecule made of the DNA and RNA of the normal ADA gene.