Which of the Following BEST Describes Attenuation of the Trp

Which of the following BEST describes attenuation of the trp operon?

A) The ribosome will stall at adjacent trp codons if tryptophan levels in the cell are low.
B) High levels of tryptophan result in continued translation by the ribosome.
C) A transcription termination sequence forms in the leader mRNA because the ribosome reaches a translation stop codon if tryptophan levels are high.
D) The structural genes are not expressed if tryptophan levels in the cell are high.
E) Regulation of trp operon expression by transcriptional repression by the trp repressor when tryptophan levels in the cell are high.