Adenosine Deaminase (ADA) Deficiency Is a Severe Form of Immunodeficiency

Adenosine deaminase (ADA) deficiency is a severe form of immunodeficiency that is usually fatal because of the greatly diminished ability of homozygous individuals to fight off bacterial and viral infections.The enzyme is necessary for the removal of the toxic metabolic product deoxyadenosine that is produced in T and B lymphocytes.Both T and B lymphocytes are produced by bone marrow stem cells, which can be harvested from patients.To restore T and B lymphocytes, a few children have been successfully treated for ADA with gene therapy, which would have been _______ gene therapy, given the above information.

A) in vivo somatic cell
B) gamete cell
C) ex vivo somatic cell
D) in vivo germ line
E) ex vivo germ line