Which of the following is true regarding the regulation of the trp operon?

A) trpR mutants that lack functional repressor have a tenfold elevated rate of synthesis of the tryptophan biosynthetic enzymes in the presence of tryptophan.
B) Tryptophan is an inducer of the trp operon.
C) trpL deletion mutants in which there is no 162-nucleotide-long leader sequence in the mRNA result in relief of repression and derepression of the trp operon.
D) Premature termination of the trp operon occurs in the presence of tryptophan charged tRNAt?p.
E) In the presence of tryptophan, the ribosome cannot translate past the Trp codons to the leader-peptide termination codon.