The genetic defect - adenosine deaminase (ADA) deficiency may be cured permanently by:
administering adenosine deaminase activators.
introducing bone marrow cells producing ADA into cells at early embryonic stages.
enzyme replacement therapy.
periodic infusion of genetically engineered lymphocytes having functional ADA cDNA.
Adenosine Deaminase(ADA) deficit can be treated permanently by bone marrow transplantation. So the correct option is b.