Answer:
They block communication between enhancers and nontargeted promoters.
Explanation:
Insulator sequences control transcription in multicellular eukaryotes. They are present near the enhancer region of a gene. When required proteins bind to them, they get activated. They interact with the enhancer region and hamper its function. Enhancer sequences increase the rate of transcription by interacting with the promoter region. Insulators block the communication between enhancers and non target promoters by various methods. For example, they can form a loop domain between enhancer and promoter which avoids them form interacting. In this way, transcription is halted.