The correct option is D Biosynthesis
In the upstream process of obtaining recombinant proteins many steps are involved, which are - development of inoculum, optimization of the culture medium and inoculum so that culture is made ready to produce the desired product in topmost quality and quantity. Upstream process focuses on synthesis of the desired product from the improved microbial strain, which is done is a fermenter or a bioreactor. This is can be called as biosyntheis.
Later the desired product is separated from the cellular debris, purified and preserved so that it can be used as per the need. These are steps of the downstream process.