Final answer:
Gene therapy is the process of inserting a healthy gene into a person's cells to counteract a faulty gene causing a disease. Although experimental, it has been effective for some conditions and is distinct from CRISPR-Cas9, which is a more recent form of precise gene editing.
Step-by-step explanation:
Gene therapy is a revolutionary genetic engineering technique used to treat inheritable diseases. This medical procedure involves the insertion of a healthy, non-mutated gene into a person's cells, effectively replacing or supplementing the function of a faulty gene that causes disease.
Commonly, the healthy gene is delivered using a vector, often a virus, which transports the gene into the patient's cells. While gene therapy is currently still experimental in many applications, it has seen success in certain conditions, such as severe combined immunodeficiency (SCID).
It is essential to distinguish gene therapy from other genetic modification technologies. For instance, CRISPR-Cas9 is a more recent advancement in gene editing that allows for precise alterations to the DNA sequence and has far-reaching potential in various fields, including medicine.
Therefore, the correct answer to the question is (c) Gene therapy, which is the method of adding a healthy gene to a person's cells to compensate for a malfunctioning disease-causing gene.