The correct option is D A, B and D
The recombinant therapeutics, which are proteins produced by recombinant DNA technology, do not induce unwanted immunological responses as is common in case of similar products isolated from non-human sources. For example, insulin isolated from animal sources has a chance of eliciting an immune response in diabetic patients.
The human insulin prepared from recombinant DNA technology is safe and less likely to elicit an immune response. In 1983, Eli Lilly, an American company, developed human insulin in Escherichia coli.
Gene therapy is a technique which involves the replacement of defective genes with healthy ones to treat genetic disorders. Retroviruses are viruses whose genetic content is made up of RNA. These viruses reverse transcribe this RNA into a DNA molecule which is then integrated into the DNA of a host cell. Since the DNA can be inserted randomly it may affect genes. In this way some retroviruses can convert normal cells into cancerous cells. Hence, the retroviruses are disarmed (removal of harmful genes) to deliver the genes of interest. This helped in reducing the chances of cancer in gene therapy by retroviruses.