Enhancers Are Considered Transcription-Control Elements That Regulate the Expression of Eukaryotic

Enhancers are considered transcription-control elements that regulate the expression of eukaryotic genes.Which one of the following is true regarding these elements?

A) They are only found upstream of the transcription start site.
B) They are never found more than one kilobase away of the transcription start site.
C) They are only found in introns.
D) They generally range in length from about 50-200 base pairs.