Option (A) is correct. The provided text distinguishes between somatic and germ-line gene therapy. It explicitly states that in germ-line gene therapy, functional genes are introduced into germ cells (egg or sperm) and 'Changes made to the germ-line are heritable.' Conversely, somatic gene therapy involves introducing functional genes into the somatic cells of the patient. Since these cells are body cells and not reproductive cells, the genetic changes are not passed on to offspring, making the therapy non-heritable.