Answer:
b) Restriction enzymes
Explanation:
Restriction enzymes are the endonucleases that recognize and cut the specific DNA sequence and breakdown the DNA into smaller fragments.
With the discovery of these enzymes, it became possible to cut the genome of microbes or any other organism at the specific site.
For example, the restriction sequence for the restriction enzyme EcoRI is 5' GAATTC 3' on one strand and it cuts between G and A of the sequence and between A and G on the complementary strand.