Answer:
Option D
Step-by-step explanation:
They are unsuitable because eukaryotic proteins before they are synthesized through transcription giving rise to mRNA and translation to proteins undergo various modifications such as splicing (removal of introns and joinimg of the exons) etc due to the presence of introns in the eukaryotic genome which is absent in bacteria.
Thus, bacteria does not have machinery that will perform this functions as it has little to no introns and the products do not have to undergo modifications like eukaryotic genome.
Thus, without this, some functional proteins will not be expressed using the bacteria expression system.