The correct option is B Prokaryotes
Restriction endonuclease recognizes specific nucleotide sequences in a DNA molecule, often a palindrome, known as its restriction site, and cleaves the DNA at a specific nucleotide within the restriction site. Restriction endonucleases are naturally present in the bacteria(prokaryotes) where they provide protection against invading bacteriophage DNA. Bacterial DNA is protected from its own restriction endonucleases, even though it contains the recognition sites, by the action of an enzyme which methylates the nucleotide at the recognition sites within the bacterial genome.