6. CRISPR/Cas9 is the most talked about techniques in the past few years for targeted genome editing. Which of the following statement about CRISPR/Cas9 is NOT correct? (A) An RNA molecule, called guide RNA, directs Cas9 to the target (B) Cas9 is an exonuclease that cut double-stranded DNA (C) The system was originally discovered as part of adaptive immunity in bacteria (D) The system has been shown to work in many organisms. (E) The system can be used to control gene expression.