How are most eukaryotic transcription regulators able to affect transcription when their binding sites are far from the promoter?

A)by binding to their binding site and sliding to the site of RNA polymerase assembly
B)by looping out the intervening DNA between their binding site and the promoter
C)by unwinding the DNA between their binding site and the promoter
D)by attracting RNA polymerase and modifying it before it can bind to the promoter