Option (A) is correct. The text defines Gene augmentation therapy as the 'Addition of functional gene to the genome'. The context further explains that the 'introduction of one or more genes' results in the genome being modified. Therefore, in gene augmentation therapy, genetic material is modified by the addition of a functional gene. Option (B) is incorrect because 'Replacing' the non-functional gene is the definition of Gene targeting therapy. Option (C) is incorrect because 'Suppressed' (blocked expression) refers to Gene inhibition therapy.