Answer:
D. They block communication between enhancers and non-targeted promoters
Explanation:
Insulator sequences are the group of DNA sequences that protect the protein-coding regions of the DNA from the surrounding regulatory sequences. Some insulator sequences are present between the enhancers and promoters of a gene. These insulator sequences do now allow these enhancers to regulate the expression of genes by sending inappropriate signals.
However, if the insulator sequences are not present between the enhancers and promoters of certain genes but are located somewhere else, enhancers can upregulate the expression of these genes.