Replacing defective genes in a living organism (especially humans) with healthy genes, and is used to treat genetic disorders and diseases.

• A. Genetic testing
• B. Gene Therapy
• C. Cloning
• D. Recombinant DNA

Answer: (B)

Gene therapy is the approach that aims to treat genetic disorders by introducing healthy copies of defective genes into a living organism, with the goal of restoring normal function. In humans, this typically means delivering a correct gene into the patient’s cells using a delivery method such as a viral vector, so the malfunctioning gene is compensated and disease symptoms can diminish. Genetic testing, by contrast, is about identifying mutations to understand risk or diagnose conditions, not changing the genetic code. Cloning refers to producing genetically identical copies of an organism or cells, not repairing disease-causing mutations. Recombinant DNA describes the technique of combining DNA from different sources to create new sequences; it’s a foundational tool used in many biotechnologies, including gene therapy, but it’s not the therapeutic action by itself. So the concept described—replacing defective genes to treat genetic disorders—aligns with gene therapy.