How does a bacterial cell protect its own dna from restriction enzymes?

a. by adding histones to protect the double-stranded dna
b. by adding methyl groups to adenines and cytosines
c. by forming "sticky ends" of bacterial dna to prevent the enzyme from attaching
d. by using dna ligase to seal the bacterial dna into a closed circle
e. by reinforcing the bacterial dna structure with covalent phosphodiester bonds

How does a bacterial cell protect its own DNA from restriction enzymes?

B. by adding methyl groups to adenines and cytosines

Explanation:

The restriction modification system is for the cells defense mechanism. This system is composed of a restriction endonuclease enzyme and a methylase enzyme and each bacterial species and strain has their own combination of restriction and methylating enzymes.

Bacteria have restriction enzymes, also called restriction endonucleases, which cut double stranded DNA at specific points into fragments. This restriction enzymes don’t cleave the bacteria's own DNA because restriction enzymes do not exist in the bacterial DNA  sequence.

But is if the recognition sequences exist but the enzyme is methylation specific. Bacteria prevent their own DNA from chop down by restriction enzyme through methylation of the restriction sites. Methylation of DNA is a very familiar way to modify DNA function and bacterial DNA is highly methylated.  

one would be wind another would be water density

gold i'm pretty sure i might be wrong