At the Transcriptional Level, How Does Tryptophan Control the Production

At the transcriptional level, how does tryptophan control the production of genes within the trp operon?

A) the trp repressor contains a high percentage of Trp residues and is thus only produced when Trp levels are high
B) without sufficient Trp, the production of the trp repressor is truncated, thus producing a protein that cannot bind to the operon, ultimately resulting in structural gene expression
C) high levels of Trp cause the repressor to be proteolytically digested
D) the trp repressor binds to the operon only when bound to Trp
E) none of the above