The correct option is C Bacteria
Restriction endonucleases are naturally occurring defence mechanism of bacteria to digest any foreign DNA molecule. Restriction endonucleases recognize specific sequences, mostly 4-6 bp, in the DNA and cut it into fragments by breaking the phosphodiester linkage between two successive nucleotides of DNA. As these restriction sites may be present in bacterial DNA itself, DNA methylase enzyme carry out methylation of DNA to protect own DNA in bacteria from restriction digestion. Thus, option B is correct answer.