What is the function of restriction endonucleases in bacteria?
a. they allow bacteria to genetically recombine with other bacteria.
b. they provide a defense mechanism against infection by viruses.

The restriction endonucleases in bacteria (b) they provide a defense mechanism against infection by viruses

Explanation:

The restriction endonucleases is a protein that is produced by the bacterias that interacts with the DNA of them and gives protection to the bacterial cell by defending against viruses.

Is important to remember that viruses go into different organisms just with a copy of DNA that wants to replicate inside of them creating more and more copies until it breaks the hosting cell and this is how the infection spreads. This protein restricts (that's the reason of its name) or stops the replication stage of the virus DNA by cutting it into many pieces stopping in this way the spread of the infection and the death of the bacteria.