BamHI is a restriction enzyme derived from Bacillus amyloliquefaciens that recognizes short palindromic sequences in DNA. When the enzyme recognizes these sequences, it cleaves the DNA. What purpose would restriction enzymes have in a bacterium like Bacillus? 

(A) They are enzymes that no longer have a purpose because evolution has produced better enzymes.
(B) They destroy extra DNA that results from errors in binary fission.
(C) They protect Bacillus from invading DNA due to viruses.
(D) They prevent, or restrict, DNA replication when the cell isn't ready to copy its DNA.