The CASPR/Cas9 system is a new, very powerful technique that can knockout genes in mice, flies, and animals that are not accessible to genetic manipulation. If you are trying to remove expression of a presynaptic protein you need to add a guide RNA and Cas9. Why do you need a guide RNA? Choose all that apply.

A) The guide RNA guides the Cas9 to the loxP site on the target DNA.
B) The guide RNA targets the selected DNA and brings Cas9 to the DNA target site.
C) The guide RNA guides CRISPR to the Cas9 protein to target the selected piece of DNA.
D) CRISPR is inserted into the genome where the guide RNA guides Cas9 to the deletion site.