Transcription activators are different from transcription factors in that a. transcription factors prevent rna polymerase binding, while transcription activators assist rna polymerase binding. b. transcription activators are required for rna polymerase binding, while transcription factors slow 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.

Correct answer is option D.

Transcription activators accelerate transcription, while transcription factors assist RNA polymerase binding.

Transcription factors are the proteins which help in proper binding of RNA polymerases in the promoter region of DNA so as to facilitate transcription.

Activators on the other hand, help in the enhancement of the transcription rate.  

Transcriptional activators are basically proteins which bind to the regulatory elements known as enhancers so as to increase the rate of transcription. Enhancers are specific DNA sequences, which may be present in the upstream or downstream region of the gene which is going to be transcribed.

It may be noted here that transcription factors are only present in eukaryotes. In prokaryotes, sigma factors are present instead of  transcription factors to facilitate proper binding of RNA polymerases on the DNA.

i believe it is "they are not used up by reactions" as the answer to your question, text me back if this is correct because i just learned this.