Which One of the Following Statements About the Transcription Attenuation

Which one of the following statements about the transcription attenuation mechanism is true?

A) In some operons (e.g. ,the his operon) ,attenuation may be the only regulatory mechanism.
B) Sequences of the trp operon leader RNA resemble an operator.
C) The leader peptide acts by a mechanism that is similar to that of a repressor protein.
D) The leader peptide gene of the trp operon includes no Trp codons.
E) The leader peptide is an enzyme that catalyzes transcription attenuation.