The answer is; C
Gene therapy is still not considered safe and has not been approved for humans, especially due to errors in inserting of DNA at the target site and also random relapse of the DNA from its inserted site. Gene therapy, however, can be sanctioned when its benefits outweigh its risks such as in terminally ill patients - with the approval of the patient and local relevant policies/authorities. Gene therapy, today, is being tested with innovative tools called CRISPR/Cas9.