The Prokaryotic CRISPR-Cas System

The prokaryotic CRISPR-Cas system

A) was discovered as a natural,evolutionarily derived immune system that arose in viruses as a defense mechanism to detect pathogenic bacteria.
B) was discovered as a natural,evolutionarily derived immune system that arose in bacteria as a defense mechanism to viral infection.
C) allows scientists to insert DNA into an organism but is limited to one group of gram-positive bacterial species.
D) is an innovative approach that allows us to reduce our use of petroleum.