Answer:
The correct option is C) a bacterial promoter sequence
Step-by-step explanation:
In the field of genetics, a promoter is defined as a sequence which initiates the process of transcription of a gene. In the bacterial cell, the promoter region is present upstream and the process of transcription won't occur unless the promoter sequences is present. Hence, in addition to our desired code of exons, a bacterial promoter sequence must be attached for the expression of the genes.
Other options like introns are not required because introns are the non- coding sequences and they do not have any role to play in the expression of genes.