The correct option is D Proteins that involved in the replication of the plasmid
The pBR322 vector is commonly used plasmid cloning vector in E. coli. In this, B and R stands for Bolivar and Rodriguez respectively. It contains origin of replication. It contains 2 antibiotic resistance genes, ampicillin and tetracycline. These antibiotic resistance genes are used as selectable markers. It has specific restriction sites for different restriction enzymes. In vector pBR322, the ‘rop’ codes for the proteins that involved in the replication of the plasmid.