In the process of gene therapy to cure ADA deficiency, which of the following cells are cultured outside the body?

Correct option is D

as a first step towards gene therapy to treat ADA deficiency, the Lymphocytes from the blood of the patient are grown in culture outside the body, a functional ADA cDNA using a retroviral vector is then introduced into the Lymphocytes which are subsequently returned to the patients, since these cells are not Immortal, the patient requires periodic infusion of such genetically engineered lymphocytes.