CRISPR-Cas9 is a genetic modification technique that edits parts of the genome of an organism. Using this technique scientists can add, remove, or modify sections of the DNA sequence. How can scientists use this technique to control gene expression?

A.) By calculating the number of genes different organisms produce
B.) By identifying how closely related one individual is to another
C.) By determining the number of chromosomes in an organism
D.) By activating or deactivating specific genes
I need help with this please.