A Doctor Studying in the Field of Gene Therapy Has

A doctor studying in the field of gene therapy has removed tissue from the patient,inserted normal genes into the tissue and then reinserted the tissue back into the patient's body,in an example of

A) xenotransplantation gene therapy.
B) ex vivo gene therapy.
C) vectored gene therapy.
D) translational gene therapy.
E) transcriptional gene therapy.