Answer:
D) transcriptional control of gene expression.
Explanation:
Enhancers as the name indicates are required to enhance transcription of a gene. Enhancers are nothing but a small stretch of DNA which may be located either in upstream (mainly) or downstream region of a particular gene. If they are distantly located from a gene then in order to cause increased transcription of that gene they form a loop to reach near the promoter region of the gene. With the help of activators and transcription factors they can enhance the expression of gene at transcriptional level.