Read the paragraph given below and answer the question. If a person is born with a hereditary disease, can a corrective therapy be taken for such a disease? Gene therapy is an attempt to do this. Gene therapy is a collection of methods that allows correction of a gene defect that has been diagnosed in a child/embryo. Here genes are inserted into a person's cells and tissues to treat disease.
Gene therapy method involves:

1. A Cloning of cells with alternative gene
2. B Delivery of normal functional gene in the embryo to compensate for non functional gene
3. C Modification of defective genes in the cells
4. D cDNA recombination