Transcription activators are different from transcription factors in that

A. transcription activators are required for RNA polymerase binding, while transcription factors slow RNA polymerase binding.
B. transcription factors prevent RNA polymerase binding, while transcription activators assist RNA polymerase binding.
C. transcription factors are required for RNA polymerase binding, while transcription activators accelerate transcription.
D. transcription activators accelerate transcription, while transcription factors assist RNA polymerase binding.