The correct option is B processing of large volume of culture
Bioreactors are large cylindrical vessels that are used for large scale culturing of cells (plant, animal or microbial cells) to obtain specific gene products for commercial use.
The steps involved in the separation and purification of the recombinant products are called downstream processing.
Micro-injection is one of the methods of DNA delivery in the host cell. This method is used to inject recombinant DNA directly into the nucleus of an animal cell with the help of a microinjector.
Isolation of genetic material from cells requires multiple steps depending on the species. It includes digestion of cell wall, cell membrane or nuclear membrane followed by the removal of unwanted materials like proteins, RNA and finally precipitation of DNA in chilled ethanol.
Hence the correct option is
c. processing of large volume of culture