Usually,bacteria Only Make Tryptophan When Tryptophan Is Absent or Available

Multiple Choice

Usually,bacteria only make tryptophan when tryptophan is absent or available in low concentration.However,a particular bacterial mutation makes tryptophan all the time whether or not tryptophan is present.What could explain this phenotype?

A) the terminator hairpin is unable to form
B) trpD is mutated
C) trpA is mutated
D) the antiterminator hairpin is unable to form
E) trpE is mutated